@icedquinn @mjdxp @newt @nytpu @wolf480pl It _can_, but it _doesn't_. Basically, on X11 it was outsourced by default (but X servers with builtin window managers exist).

And that is why it is currently in practice harder to have custom window management on Wayland. Wayland was MEANT to bring forth GNOME world domination, alternate compositors were seen as a bad thing to happen (see also: client side decorations, which could only work well in a single-DE environment).

But indeed - someone definitely could make a "W server" that outsources window management and decoration to a subprocess with a clearly defined protocol. No such protocol has been defined yet though, so there we are. wlroots, being a library and not a protocol, comes closest.