This is absolutely true even for Nikons and Canons of the world.
I'm always baffled about the obsession with open source for photo editing workflows on a desktop. From "I just want to get stuff done" OSS is just junk. It is a better junk than it was before, but it is still junk. And why would not it be? It is all about optimizing for the experience and there's not a single piece of open source software that is optimized for user's experience. Why on earth do we think this -- a fairly complex type of software -- would be any different if we cannot get themes in GNOME work consistently?