Wayland Weston Compositor's Next Version Will Be v3.0

[starshipeleven]

Why anybody would care about a stable API for userspace components?

Because otherwise userspace components don't talk with each other. In this case, userspace components don't talk with the compositor.

All apps should all be containerized, like in Flatpak; and base OS devs can update libraries whenever they choose to.

If apps are containerized enough for this to not be an issue they need to carry their own userspace with them Steam-style.
Then the OS does not need libraries at all (apart from basic stuff like glibc or things it needs for itself), btw.

[uid313]

Who is using Weston? Gnome uses Mutter, KDE uses KWin. Where are the synergy effects?

Nobody is using Weston, it serves as the reference compositor to Wayland.
Weston is to Wayland what twm is to X.