Linux

as a matter of fact Cinnamon is also working on wayland (and here by wayland I refer to the whole thing not just the compositor), with the first release having come out recently iirc or coming very soon anyways and so are other desktop environments, and if they aren't likely someone else will port them over if enough people care (such is the beauty of open source). It's not just KDE and GNOME (which still account for a vast majority of users btw, if you choose a less popular DE you should expect slower development and less support it's not something new or crazy or wayland's problem it's normal).

Because the bright people who did this decided they needed to throw the baby out with the bathwater on X. They couldn’t possibly find a way to ditch only the obsolete parts and fix the problems and maintain compatibility as much as possible. No, everything had to be rewritten from scratch.

If that was something possible/sensible to do, someone would have done it in the past 11 or something years of xorg being well on its way to the shitter? Like I get that companies make a lot of shit decisions due to money but clearly if abandoning deadware was chosen over resurrecting parts of it there's a good reason. Also pretty sure all of it is outdated my dude so your point doesn't stand. To my knoweledge Xorg isn't very modular but I may be wrong here.

So here we are 15 years later, with another 5 or so to go until the whole Linux desktop ecosystem will be thoroughly redone.

Not a bad thing. Just like it wasn't a bad thing when computers went from just the shell to a GUI, from tapes to eventually hard disks, unix to linux, etc. Xorg can't support HDR nor lots of other things and in all these years nobody has managed to add them, not a company, not the community, not some schizo programmer with led unix socks and a custom tailored furry suit, that's why wayland was invented and what eventually will run on everything minus abandonware. Xorg has been on its way out for years now, Wayland is perfectly usable (with notes to be made for GNOME's implementation on the developer's side and Nvidia on the regular user's side) for the vast majority of users. What RH (Valve, and others) are doing is simply pushing people to get a move on and focus on wayland instead of passively waiting for it to just get better while they just stay in Xorg forever.

And btw nobody is gonna be stopping you from putting Xorg on your machine if you want. I'm using Xorg right now, merely for the sole reason my laptop with its 6GBs of RAM is too weak to run games on wayland yet due to XWayland (which again would be an easily solved issue if instead of having to make things for Xorg in mind they were made with wayland). But the switch to wayland is inevitable, not sure what you were expecting honestly you can't keep a service from the 80s running forever when a better alternative finally arrives.

In fact, as I mentioned, keeping something on life-support this long has only been damaging as it doesn't incentivise people to actually develop for wayland as much (even if they wanted, most its users were on Xorg and havng to choose one or the other thing they're forced to choose Xorg, for example), granted it's not the only disincentive there are some that are due to wayland's implementations and particularly GNOME's but without the move RH and others made the decisions on how to address these issues were just gonna be postponed ad infinitum.