It would require that Wayland be aware of internals of the "compositor". Instead of that, Wayland is only aware of surfaces, which it can guarantee can be stitc

It would require that Wayland be aware of internals of the "compositor". Instead of that, Wayland is only aware of surfaces, which it can guarantee can be stitched together within a certain time budget. Hence none of the tearing that is unavoidable with X11. A window close event goes to the "compositor" of a surface, without being aware of which PID may have caused what is currently rendered on that surface. Windows and macOS do the same, if only because they have a single "compositor"/window manager.