I dunno: I have never ever wanted to make a compositor -- which, to me, feels like a really boring piece of graphics infrastructure -- and yet I have used multiple window managers over the years and have absolutely wanted to make my own window manager? In X, making your own window manager was so popular of an activity that it honestly felt kind of unreasonable just how many window managers existed, and yet everyone used one of a handful of compositors and I'm honestly not sure why anyone in their right mind would bother making their own display server?