>The greatest problem with the Wayland protocol is how much work a compositor has to do. Requiring every window manager to also have to take on tasks like processing keyboard and mouse input is a massive tradeoff for what Wayland offers.

No, not really. Everything that Wayland does is stuff that X11 compositors were already doing. With those the compositor is already taking on all processing of input, and the X11 server is only creating an additional unnecessary step by passing all the input through. Thus why that extra step was removed in Wayland.