There is fragmentation in FOSS image editing. There's GIMP, Krita, Pinta, RawTherapee, DarkTable, Digikam and a few others. But it's good fragmentation. FOSS image editing is in fact in a much better place than FOSS video editing right now.

GIMP is focused on being a good general purpose image editor. Krita is focused on being a good digital art program. Pinta is focused on being a more basic, beginner-friendly image editor. RawTherapee/DarkTable/Digikam are focused on professional photography, with the latter in particular focused on library management. And they all do at least a decent job at accomplishing what they set out to do. If you as a photographer find that GIMP just isn't doing it, you can try DarkTable and will likely find what you were looking for. If you're an artist and GIMP isn't good enough, you can simply use Krita.

Where's this variety with video editing when everything is just trying to be a general purpose video editor? I'll acknowledge that the "simplified video editor" use case is covered by OpenShot and Pitivi. I'll also acknowledge that there are dedicated editors for animation (OpenToonz, Krita) and VFX (Natron). What about everything else? Instead of having different video editors for different use cases, you have at least six editors trying and failing at trying to do everything.

Say you aren't satisfied with Kdenlive, what should you use instead? Maybe Blender has the feature you want, but then maybe it's missing another feature you depended on in Kdenlive. Maybe Cinelerra has both features, but is missing a third one you also need. By the time you've tried all of the available options, you've wasted a lot of time and have found no editor suitable for your usecase. Do you just constantly switch back and forth between two or three editors which combined have all the features you want? Well, you can try. Switching between image editors is easy. There are many standard lossless formats you can export to and you can even directly import GIMP or Photoshop project files in other editors like Krita and Digikam. How do you open your Kdenlive project in Blender or vice versa? Should you encode every time you want to switch? Lossless video can easily take hundreds of gigabytes, lossy video means a loss in quality, both mean several hours spent waiting for encode to finish. Obviously not viable. So really you have to pick one editor and hope it does everything you want, because switching mid-project is impossible.