GIMP hasn't even migrated to GTK3 yet. The upcoming GIMP 3 will finally use GTK3 and is slated for release in a few months, but this is years after almost everyone else. Certainly in the case of GIMP I think "lack of resources" can be substantiated pretty easily. IIRC GIMP 3 will also get Wayland support – I'd have to check to be sure.
I'm less sure about XFCE or Enlightenment. Judging from [1] the XFCE people have been working on it since Feb 2021 (when that page was created), but real issues still remain, and I'm not surprised that "let's do a substantial rewrite of much of our codebase from something that works perfectly fine to ... something else that works perfectly fine" is not hugely top priority for a fairly small project like this. Call that "people being roadblocks" if you will, but that doesn't strike me as fair. Neither of us get to decide where these people spend their time.
I'm less sure about XFCE or Enlightenment. Judging from [1] the XFCE people have been working on it since Feb 2021 (when that page was created), but real issues still remain, and I'm not surprised that "let's do a substantial rewrite of much of our codebase from something that works perfectly fine to ... something else that works perfectly fine" is not hugely top priority for a fairly small project like this. Call that "people being roadblocks" if you will, but that doesn't strike me as fair. Neither of us get to decide where these people spend their time.
[1]: https://wiki.xfce.org/releng/wayland_roadmap