I just meant to point out the complexity of the transition Linux has gone through... The transition from X11 to Wayland is still a thing and most Environments / Window Managers still use code from both technologies.

However, you are right, there is no such thing like display server AND compositor.

> and window manager doesn't deal with mouse movement

And that's causing one of the problems I described above, when changing window focus while scrolling. The driver just sends scrolling events, regardless of the window focus, so it keeps scrolling, when you trying to "simulate" kinetic scrolling.