Sure, but then it spread on Facebook in several languages, and on other forums (see the bump in the participation curve).
Forget about the “professional” word then. I just mean people able to see a red channel clipping or differentiate cyan from blue or perform a skin editing that doesn’t turn the face into pure wax. That is, people who have mastered their stuff above average.
Hi 
Given that Windows packages for dt are a relatively recent phenomenon, this suggests that the overwhelming majority of long-time dt users are Linux users. This alone would suggest that the user base would be more technical than the overall population of photographers.
I’m a hobby photographer from India. Amongst my very limited photography circle here, a few are professionals who pay for Adobe, a few are hobbyists who only bother with snapseed on their phones. A small percentage do use pirated Lightroom.
Before jumping to Darktable, I was using Adobe’s photography plan. It is actually quite cheap here for anyone considering this as an serious hobby. ₹800/month is less than one movie outing. And there a shit-ton of tutorials on YouTube which add to the comfort level.
As @aurelianpierre is talking about statistics … however, every voice counts :D.
I am sure for most of these people, darktable is way too technical. They may not care about dB values but are happy pushing sliders from 0 to 100. About the complicated stuff such as colour management, there are pre-baked solutions that do not require technical understanding. Basic lightroom editing of many professionals means pushing 4 sliders towards what they call “dynamic D”, I think it’s black, white, clarity, and whatever. Plus white balance and maybe a nik preset.
There are many other reasons for people sticking with adobe, and at least for me, the selling point of free software is not the price tag but the control over my data and that there are no lock ins. Plus many technical reasons.
Among the reasons sticking with adobe I am often told:
I know some of them are stupid reasons, but that’s what arts and design people tell me.
There might be a bit of a skew due to users willingness to participate. I shared this on my photogroup among people who use many different apps ( darktable is often recommended there, but we also have bunch of pros doing adobe and still recommending darktable/RawTherapee) and it seems like people didn’t even bother with it (“it’s in english!”) or just went into “i won’t be filling no surveys” mode…
The result is not really surprising. For most image editors - if they really can be called image editors - good enough, simple to learn and to use is the maxim. Thats why canon puts the green rectangle program even on their most expensive camera lines …
Professional photographers worries about time, not features. The must features are important, but these are available in any commercial raw converter or image editor. If they can edit their images several minutes faster to fit the customer’s needs they will use the tool, that give them just the required functions. If they have to pay for it - it’s worth paying for it.
Thats also a reason, why sony isn’t able to blow canon or nikon out of the pond: the last percent of dynamic range isn’t in focus of professional photographers, they earn their money with daily business shots where the ooc jpeg must be already perfect. A Raw converter is mostly used while importing into Photoshop where the main work - retouching etc. is done.
Darktable gives features to bring out the last percent of a raw file - thats for enthusiasts, not for the guys where time is money
But it could be. A tool could serve both requirements. Some actions were already taken, e.g. basic adjustments module.
To fully understand the topic, maybe each photography genre has to be analysed separately. It would be great to do this and discuss it with people from this genre.
A few days ago my colleague photographer asked me to find a solution for him to edit a series of photos he took at a concert under rather poor lighting conditions. He was under pressure because he had to deliver the results quickly.
I recommended him darktable and we met yesterday at noon to demonstrate and explain how he can use darktable. I briefly explained the technical background to him and showed him how to get good results quickly with a few modules. He then processed a couple of pictures with my assistance and went home.
He called last night and thanked me for everything going well and smoothly. Above all he praised the possibility to transfer the history stack to other photos with similar motifs and output conditions and only occasionally had to make adjustments. That saved him a lot of time.
I dare to doubt that he would have been able to do this on his own if he would have only relied on the documentation and information from the internet.
I believe that Free Software suffers a lot from the fact that - for understandable reasons - it cannot provide the necessary demonstration, training and support to bind people to software. It is more or less left to luck whether someone who has come across Free Software takes enough time to get acquainted with the possibilities and functionality.
Just to note - for every day of material on youtube alone on lightroom editing, there’s a minute of darktable editing and no more than ~30s of rawtherapee editing judging from my rought search recently
Tutorials have to be done with great images, not with mediocre ones. @s7habo, you are doing a good job in that regard, but many darktable tutorials are done with bad images which would not attract people.
and (un)fortunately darktable received a lot of improvements, so older tutorials might be not that helpful yet …
But free non commercial software usually doesn’t focus on a broad user base over giving the best available tools to enthusiasts (because the developer are in this user category) …
that can be seen in the results - engineers likes high sophisticated tools 
For me personally this last percent is the main reason I’m using dt. Working on thousands of digitized diapositives and negatives from the last 60 years is a really challenging task. One has to fight against color casts, film grain, dust, fungus, scratches and other signs of aging. For this task, the fine control over the large number of parameters darktable allowes, is essential. Presettings and automated tasks and “prebaked solutions” almost always fail.
Yes, it takes time to learn and understand the concepts behind darktable. And it helps having some knowledge in math and physics. But if one went through this learning curve, in my opinion, darktable is the most powerful tool doing really sophisticated tasks.
I think darktable serves a niche and should not strive for a competition for “ease of use for everyone” for the price of neglecting it’s strength of performance in doing ambitous tasks.
DANGER: opinion post ahead
I’m self employed doing multimedia and web dev… I do photos for clients too, sometimes for the government, ministry of tourism… blah blah… self taught…blah blah…which all somehow makes me a professional or at least my clients think I am. Here are my thoughts (oh boy!).
I think that most important thing for professional photographers and why they choose Lightroom is its fast workflow. It makes a big return on investment. For most images, you just push a few sliders and you’re done.
If there was a program that edited images by itself without user input, we’d be using that.
Other photo software is heading that way by using AI and neural nets.
I tend to do most of my edit in the raw development tool or as much as I can b/c Gimp is destructive and Ps doesn’t perform well in a VM (I’m on Linux). And with Lightroom it’s way faster than with DT.
I also tend to do very radical edits that almost look like composits b/c it’s what instagram kids do and what my client is seeing from others so he wants the same.
So in Lightroom, I’ll often times use a drawn mask almost as a painting brush to fake a sunset or whatever.
In the recent months I’ve started promoting DT to my photographer friends etc. Yesterday we tried to achieve the same exact edit that one friend did on Lr. It took him 10 min on Lr, it took me at least an hour on DT to do the same. Still couldn’t quite get copy it 100%. And he told me exactly what he did in Lr before I started editing. But, maybe I’m not skilled enough tho I really doubt that is the case.
1. masking
The amazing Darktable parametric masking is also huge pain when it comes to any visually bussy scenes. As much as parametric masking helps, often times you can spend hours tweeking it and drawing it and still not get the right mask. Darktable desperately needs a painted raster mask to complement it’s vector masking and parametric masking.
Now, let’s say you have your mask, you will spend at least 20 min to achieve the result you wanted b/c you have to duplicate multiple modules, set it to the same masking, move between the tabs and between different modules countless times until you achieve the desired look.
Yes, it gives you absolute control but it’s slow as a snail, it’s impossible to work with if you have like 500 images from an event that you have to deliver the next day.
2. Tool controls
Darktable is a software that gives you the absolute control and that I enjoy using when I have the time that I can spend on it.
Lightroom on the other hand helps you every step of the way, it takes away the hassle of needing to purposely set every single parameter of the algorithms and having to understand what’s uner the hood or how the software will behave, perform, what kind of result will it spit out, the pipeline order etc.
When I’m doing images for a client, I don’t want to be thinking about anything else but the image I’m working on, the time I’m spending and the money that I’m getting. It doesn’t have to be the best possible edit, I’m not payed for that. It has to be an image good enough to achieve desired results whether that’s market something, document something etc.
Professional photography imo is not art, it’s an industry job.
3. misc
Would I ever give Darktable to an employee?
Will Darktable ever be suitable for professional photography at scale?
Who is Darktable for imo?
4. All what I’ve just said is a bunch of bs
Where I’m at now?
With all this said. I still can’t really point to any particular issue and propose a fix since I really don’t want the DT to get so abstracted like Lr, but on the other hand I would love to have a very fast workflow.
For now I’ve been opening smaller bug reports and feature requests that actually add up to help a lot in the end. So I’ll continue to do that for now until we all get a better idea where things need to go.
TL/DR: Darktable workflow is slow, Lightroom workflow is fast. Darktable gives me control, Lightroom is too abstracted. How to get Lightroom’s speed in Darktable w/o losing the control it gives?
I’m in the process of creating a website and a YouTube channel where I’m hoping to feed my indoctorination bs to ppl so stay tuned XD
I’m just being a bit lazy now so, Soon™
I agree 100% with your thoughts, not because I’m the same industry as you, but because I’ve been working closely with the Communications Department at work, and I can confirm most of what you said.
Only when I started working closely with them I may have mentioned foss raw editors once or twice, mainly when they were bidding Adobe licenses renewal.
Since then, I never mentioned it again, because I realized what they wanted to achieve:
When I join the managers meetings and see how they are pushed for fast results, I don’t even dare of bringing the commercial x foss debate to prove that they could achieve the same results for no money, because it would be waste of time, and they would probably kick me out of my job.
How about offering one of your commission works as a Play Raw, with your Lightroom editing for comparison?
You made me curious if and how quickly can be achieved with darktable what you do with Ligtroom. 
How fast ? It’s possible to develop a really fast workflow in dt now, I can show you. Maybe not 10 s fast, but 30-45 s fast. That’s still 120 pic/h if edited without copy-pasting.
darktable caters to a very small niche - to advanced photographers. People who are unhappy or not sufficiently served with smartphones and who spend thousands of Euro or whatever on camera gear and then recognize that even the most advanced image processors are not enough and they need to convert from RAW data all by themselves.
On top of this, the dt-users are most likely running Linux and that is something you either get in contact with because you are a total computer-nerd, on university - or both.
And finally - after looking into fractions of a fraction of a fraction - our user lambda needs to chose darktable over RAW Therapee or whatever alternative there is…
The idea and necessity of open-source is not understood in countries where no one ever has heard of a punishment for violating a license agreement. I can witness under oath that five years ago the secretary of transport of a european (but not EC) country operated a non-licensed copy of Win 7 on his official “office” computer. I clearly saw the warning/announcement on his monitor.
There is no “legal” issue with Windows or PS in Third-World Countries. Neither MS nor Adobe spend a single cent on legal defense of their license in those places - so why use something as “complicated” or “outlandish” as Linux? It’s all free here!
Heck - my own son has a master’s degree since 2016 and tells me that he “smartly” managed to get his Adobe student license extended for another year … we - as in people who give a shit - are a tiny, tiny minority!
Isn’t that utterly fascinating, that developing better software for free, is a niche for rich educated folks;
Whereas people who earn their money with said software don’t care because the marginal cost of software is almost zero and time is more important than money.
And people who can’t afford software don’t care because there is no distinction between free and stolen to them.
Only us rich educated people have the leisure to care about freedom above money, and can freely spend the required effort to develop and learn FOSS software.
So it’s not about democratization of software, but about toys for the rich. Which is entirely fine by me. But implies either, different priorities if we want to target “normal” people, or a full embrace of our bubble and a more myopic reevaluation of our priorities.