It's certainly part of the story. But even after using (and mostly loving) Gimp now for years I still dislike the way it opens each image in an own window, especially when working with lots of open images. I can't just hide all gimp-windows in the background when switching tools - I have to hide each image one-by-one. Usually it's easier hiding all desktop windows and bringing up the other application I need afterwards. What irritates me even more is when I have to hunt for the tools-window of gimp behind some of my images.

But I don't know if Photoshop would be nicer in that regard , I haven't used that in a long time.