>X11 is one of the few APIs that had a really long run and that everybody in the community agrees upon
Outside of a very small niche of obscure window manager developers, this isn't true. GNOME and KDE have been trying to get rid of it for decades. The glaring flaws in the API have been known for that long.
>38 years of backwards compatibility and still being able to deliver performance
No, the Xorg server actually lacks backward compatibility with lots of non-standard X11 extensions that for whatever reason were either removed or were never merged upstream. At the time some of those may have been the best way to deliver performance on specific hardware but, like anything, they didn't hold up and were thrown away. It wasn't because an IBM/Redhat or Collabora employee said so. See also https://en.wikipedia.org/wiki/X_Window_System_protocols_and_...
Both are are really bad desktop environments and part of the reason the FOSS desktop never took off. Also they are mostly developed by full time paid employees with zero community involvement. As such they are the small niche.
> The glaring flaws in the API have been known for that long.
X11 has flaws but I wouldn't call them "glaring". They are a nuisance at best. You don't pay for functionality you don't need. Wayland has glaring flaws because it does not provide and standardize functionality that people need. It also has severe technical flaws like implicit sync which makes all your application stutter when one application has high GPU load.
> Xorg server actually lacks backward compatibility with lots of non-standard X11 extensions that for whatever reason were either removed or were never merged upstream.
Great, so there is a regular organic and efficient clean up process happening that keeps the unused or unpopular stuff out of X11. There shouldn't be much "old cruft" around then. If this is the case, why do we need Wayland?
>Also they are mostly developed by full time paid employees with zero community involvement.
No. Both of them have a good mix of community contributors to do the fun stuff, and paid employees to do the annoying tasks no one wants to do for free. A good project needs both. Are you really suggesting that another desktop is somehow going to spring up and succeed with no paid employees and no business case? If what you're saying is true, wouldn't that have already happened and left GNOME and KDE in the dust long ago?
>You don't pay for functionality you don't need.
You actually do if you're maintaining the X server and protocol.
>Wayland has glaring flaws because it does not provide and standardize functionality that people need.
These can be fixed by extending the protocol, unlike in X11 where the flaws can't be fixed because they're built into the core.
>It also has severe technical flaws like implicit sync which makes all your application stutter when one application has high GPU load.
This is actually a kernel/driver problem. It also happens in X11 if you use a driver with implicit sync.
>Great, so there is a regular organic and efficient clean up process happening that keeps the unused or unpopular stuff out of X11. There shouldn't be much "old cruft" around then. If this is the case, why do we need Wayland?
No that's not what's happening either. Lots of current X11 extensions (such as Big Requests, XC Misc, XFixes, XSync) actually exist only to paper over old cruft in the core protocol that can never be removed. It's possible to remove other extensions from the core and still keep the core intact. When the core X11 protocol itself becomes unused and unpopular (which it is) then it's time to remove the whole thing.
Outside of a very small niche of obscure window manager developers, this isn't true. GNOME and KDE have been trying to get rid of it for decades. The glaring flaws in the API have been known for that long.
>38 years of backwards compatibility and still being able to deliver performance
No, the Xorg server actually lacks backward compatibility with lots of non-standard X11 extensions that for whatever reason were either removed or were never merged upstream. At the time some of those may have been the best way to deliver performance on specific hardware but, like anything, they didn't hold up and were thrown away. It wasn't because an IBM/Redhat or Collabora employee said so. See also https://en.wikipedia.org/wiki/X_Window_System_protocols_and_...