[Beltalowda]

GIMP doesn't have that many contributors; it's hard to estimate the total contributors at a quick glance because so many committers only commit translation updates, but it doesn't seem more than about 20 over a 25-year period that have some serious (non-drive-by) contributions, all active at different times. Just 4 people seem to account for well over 75% (3 of which are no longer active). At the moment it's about 4 people, give or take, who work on it somewhat regularly.

Is the state of GIMP annoying and frustrating? Sure. Is it a failure to more effectively allocate resources to work on a fairly critical piece of software? I think so. But if you look at the technical side of things it's not that clear-cut at all. Remember that back in the day GIMP had to invent their own toolkit (GTK).

Being a webapp is probably an advantage here. What's the big thing for GIMP 3? The port to GTK 3. Does that really add anything for users? Not really, as such. But that kind of stuff is quite a big time-sink and doesn't really add any features. Same with the new build system, wayland support, i18n changes, etc. which doesn't really "do" anything other than keep the thing from bitrotting.

Photopea has had someone work on it full-time for over 5 years; if you put that against the evenings and Sundays that people work on GIMP, and consider all the "plumbing" they had to do that Photopea doesn't have to deal with then the differences in time spent are probably much smaller than you'd might suspect at a glance.