I’m not an expert but if believe the challenge is when

* you try to do GPU compositing things get more complicated. You mention you have no interest in GPU compositing but that’s quite rare

* a lot of such exploits come from confusing the kernel about the buffer to use as input/output and then all sorts of mayhem ensues (eg giving it an input buffer from a differ process so the kernel renders to the screen a crypto key in another process or arranging it to clobber some kernel buffers)

* stability - a bug in the compositor panicks the entire machine instead of gracefully restarting the compositor.

But ultimately you’re the one claiming you’re the domain expert. You should be explaining to me why other OSes made the choices they did and why they’re no longer relevant.