Well, that's exactly what the article is about. Wayland put all together into one process I order to avoid unnecessary context switch. This protocol aims to keep the performance advantages of Wayland without giving up on separation of graphics c server and window manager.
I was responding to this comment in the article and wondering about the historical context:
> Although, I do not know for sure why the original Wayland authors chose to combine the window manager and Wayland compositor, I assume it was simply the path of least resistance.