This is a huge reason why we have nice code editors nut no Photoshop alternative for example.
Mostly speculation:
I think that's just a time and money issue. Blender was behind Autodesk for a long time, but nowadays it's a real alternative that offers extra features.
Gimp, Krita, and other Adobe alternatives are still in that earlier phase where they're not yet good enough to get funding from studios and companies using it.