The term "compositor" refers to a program that is significantly broader in scope than an X11 window manager. You can write the most basic but somewhat useful WM

The term "compositor" refers to a program that is significantly broader in scope than an X11 window manager. You can write the most basic but somewhat useful WM in about 50 lines of C, and literally *all* it has to do, is to respond to new windows being mapped. A Wayland compositor on the other hand has to do approximately half of the work of an actual full-blown X11 server. This is why almost every WL compositor out there is using wlroots - which continues to advertise itself as "60k lines of code that you'd have to write anyway". Calling WL compositors "window managers" is somewhat like asking where's the horse in that car.