This article was written in the sense of bashing gnome but yet some points seem to be valid. It explains the history of gtk 1 to 4 and the influence of gnome in gtk. I’m not saying gnome is bad here, instead I find this an interesting to read and I’m sharing it.
No, they don’t exist because of Gnome lol.
Source on it reinventing the wheel every 2-3 years?
Gnome 3 was well over a decade ago. It’s worked the same way ever since.