Whenever I see posts like this my immediate reflex is to remind the complainant to have a little respect for the creators. But it’s really hard to disagree with this…
It's sad because it's not that the app isn't powerful, it's that it's obtuse to anyone but diehards.
For example when they introduced the single window mode as default, I view it as a regression only because people can't use a window manager properly or pretend to do professional stuff on what is just a glorified video game console OS with a shitty windows management. Thanksfully they kept an option to keep using multiple windows mode for us.
In that time I used GIMP a lot and was a good moderate level user probably, but the interface kept getting in my way (unlike Photoshop were I was able to reach almost a flow state of doing things at that time)
Eventually I just moved on, but I can’t fully shake the feeling that GIMP could have been so much more. Godot and Blender which others mentioned just have done so much better in that regard. Blender had the suckiest of UX/UI but even in the face of much/some “old timer” resistance they made something that most hail as a success now.