That's a big problem. When things become an optional extension for a compositor, that means you cannot reliably deploy something that depends on it to Wayland.
At this moment, things in the wild are coupling themselves to libwayland-client and in practice ossifying its ABI as a standard no matter what the wayland orgs say about it.
I can't count the number of things that either no longer work or no longer even exist at all because of nothing other than the fragmented and ever-changing nature of the web. Aside from sites and apps that required flash or silverlight, I have several different pieces of expensive aactual hardware that either partially or wholly became unusable because the built in and non-updatable web interface requires an old version of java or activex.
Indeed we do all know how that went. It went like to total dogshit.
Do you mean the Window Manager layer?
That sounds like a different way of saying "impossible".
In X11 I can create an automation tool that works regardless of the underlying WM, or even if there isn't an underlying WM.
Can't do that with Wayland.