Because Wayland only does essential low-level stuff such as display and graphics it forced people to start coming up with a common Linux desktop (programming) interface out of nowhere to basically glue everything together and make programs at least interoperate.

Such an effort to rethink Linux desktop alone could've been a major project on its own but as having something was necessitated by Wayland all of it has become hurried and lacking control. Anything reminiscent of a bigger and more comprehensive project is in initial stages at best. If Wayland has been coming on for about ten years now I'll give it another ten years until we have some kind of established, consistent desktop API for Linux again.

X11 did offer some very basic features for a desktop environment so that programs using different toolkits could work together, and enough hooks you could implement stuff in window managers etc. Yet there was nothing like the more complete interfaces of the desktops of other operating systems that tied everything together in a central, consistent way. So, Linux desktop interface was certainly in need for a rewrite but the way it's happening is just disheartening.

Nobody has a user-space stick big enough to force things in the Linux world.

When Apple dropped the old audio APIs of classic macOS and introduced CoreAudio, they pissed off a lot of developers, but those developers had no choice. In the GUI realm, they only deprecated HIKit for a decade or two before removing it (if they've even done that), but they made it very clear that CoreFoo was the API you should be using and that was that.

In Linux-land, nobody has that authority. Nobody can come up with an equivalent to Core* for Linux and enforce its use. Consequently, you're going to continue to see the Qt/GTK/* splits, where the only commonality is at the lowest level of the window system (though, to Qt's credit, optionally also the event loop).