The way I work is...
I pick an image and process it, then in file browser I copy the processing to all other images of similar condition, mainly just having to fine tune exposure and black point. I do this for each group of "similar condition" images for that day.
I load a profile and then continue manually, I have never worked the other way round. i.e. manually adjust some settings, and then load additional settings from a profile.
I have created multiple of my own profiles, which are all intended as starting points. I have set my most common starting point as my default processing profile. If I load a new profile, it is because I want a different starting point and I want the new profile to completely reset all settings.
With the option for partial profiles only, I would have to update all my profiles every time a new feature is added. To make sure it resets all settings.
I can see that the dynamic profile feature offers a new way of getting to the starting point, but I may still want to reset to a different one.
I'm not saying the way I work is the best way, or that there aren't other ways of working, but why remove a feature that is as unobtrusive as this.
Hope this helps clarify.
Of course, if no-one else uses fill mode, then don't let me get in the way of progress