My comments are based on my observations. I don’t have much experience with apps and development.
I don’t think that there is such a thing as an all-in-one piece of software even in the commercial world. This is a generalization of course. However, if you look at any software company, chances are that you would have a litany of offerings.
Say, for example, Adobe. Look how many apps it has in total (I bet most of us don’t know most of them, except for the popular ones)! No app does it all. Very likely, you would need at least Photoshop and Lightroom to do the job. Same with Illustrator and InDesign. I find that I would need both, not one or the other. Making features missing in one app and available in another partly has to do with getting the customer to spend more money (before Adobe turned to the subscription model). It also has to do with keeping software development and quality control manageable.
Oh, the subscription model. The app world is moving in that direction. Something to do with job security… Lots of other industries do that and are quite successful, although the poorer customers are worse off due to having to pay the constant upkeep, along with their normal bills. It does have its benefits, like addressing the problem of having to cripple software to entice more purchases. Adobe customers don’t have to deal with that any more, though there are subscription tiers.
This model of course was a big turn-off for many customers who proceeded to migrate to other software ecosystems. I think that is why Affinity means something to many people. In certain respects, FLOSS software, even though they have their own issues, are not hostage to the issues that I described above.