Yes, it's neat that you can still compile and run ancient Win32 programs on modern Windows, but maintaining all of that compatibility is a burden Microsoft was able to bear. The open source community is still struggling to try to provide a compelling desktop experience without this burden.
Can you run ancient old Linux graphical software? Well, to an extent... Yes. Is it easy? ...No. At least, it's certainly not as easy as installing stuff from your OS vendor directly. As far as Wayland goes, there are no plans to get rid of XWayland any time soon. I'd wager it will remain in the toolkit for decades to come, and if anything, XWayland support keeps getting better rather than worse; just look at what KDE has been doing.
Usually, when I want to try to run something really old I'll use the Docker debian/eol[1] images. Getting X11 apps to work inside of Docker requires a bit of fidgeting, but once you have it working, it's relatively straight-forward to install or build and use software inside of.
The Linux desktop is necessarily going to keep going through large breaking shifts because well, it sucks. It needs to go through breakages. When the new thing also seems to suck, that hints that it might need to continue to break more. It's going to take a while to iron things out, especially because designing systems is hard and sometimes new ideas don't wind up panning out very well. (This has caused a lot of trouble with Wayland where a lot of ideas, indeed, did not pan out super well in practice in my opinion.)
That said, I think we can do much work to improve interoperability with older software, and ensure that it can continue to run in the future. But, it doesn't have to, and really, shouldn't work by keeping everything else from moving.