I think it's totally fine and normal for multiple OSS tools existing in the same space.
Krita is almost 20 years old and is more focused on painting than on image editing – but personally, I use it for both, liking the UI much more than that of GIMP.
Back in those days, GIMP was just barely usable for painting, and Krita was mainly good for crashing. Both have come a long way since then. GIMP is still mainly an "image manipulation" program. It got better at painting, too, but you probably want to give Krita a try for that.
