To be fair, I believe PSP7 had batch processing too, but I do find things like ImageMagick extremely useful as you can add right click triggers for batch files that do custom operations.
The biggest problem I find with GIMP is its filters seem to be all over the place. Just finding sharpen/soften options is confusing, I'm not sure I ever found them.

Whereas in PSP7 its very straightforward.
I think part of the difference is in Linux you kinda get used to some element of having to use the right tool for the right job, rather than everything being in one neat package. That's naturally frustrating if you're used to everything is one place and just working, doubly-so if you're doing time sensitive work so just don't want the hassle of learning what the best tool for the job actually is.