Whatever the issues with X11, it was properly designed. Wayland is the kind of software that adds features with nobody looking at the consequences. Who knows what they will break next version.
From all the criticisms leveled at Wayland, this is definitely the strangest I've ever heard.
I really cannot thing of any existing functionality ever broken by a new release of wayland-protocols, neither by a plain bug nor by a bad interaction. No doubt someone else will be able to recall an example, but it's really not a common thing.
This is partially because the governance model and community mindset is the opposite of what you describe. Inclusion of new protocols in the stable release requires existing, proven implementations and consensus across multiple implementors, making it a high bar. New proposals run a gauntlet where pretty much everyone is looking at the consequences in detail.
In fact a more common criticism of Wayland is that the focus on high quality and the consensus requirement are too strict and have slowed down filling in feature gaps users need filled faster. This argument I think can be successfully defended against - mainly, that it helps avoid the mess X11 became over time -, but at least has some basic merit in reality and is an avatar for genuine user pain.
As for X11, as someone who had to implement a lot of X11 specs over the years, I can tell you that their provenance between X11 itself as well as ICCCM and EMWH had plenty of super dumb ideas and cruft and inconsistencies from lack of foresight and eventually datedness. You don't want to see the towering stack of hacks and heuristics we used to have to ship to make X11 behave somewhat consistently and sane :)
In short, with all due respect, but I think you really don't know what you're talking about. We really should resist this type of narrative reality distortion field on an engineering forum.
That high bar is GNOME having an uppity whenever a Wayland protocol is suggested they don't like, that even if is accepted, if Mutter doesn't implement it then its dead in the water given its the de facto default compositor on unfortunately what people consider "Linux", aka Ubuntu.
e.g. DRM leases that only got changed because Valve has the bigger underwear. Expecting games to implement DBUS (incl. when running under Wine) to access VR headsets just for GNOME is nuts.
The government model needs a change that stakeholders who ship devices to the end users that rely on them have more of a say, whether that's Google, Valve etc. Valve is now backing and pushing KDE into average joe end users is a telling.
