There is no reason for a display protocol to know about these things. At most it is responsible for giving access to a window’s/screen’s buffer and then any app can do whatever they want with it, eg compress it and stream it (which as I wrote in an other topic is usually better performing than today’s frameworks over whatever remained of X remoting, with bitmap transfers and the like)

Quite true. I've have to switch my desktop back to Windows because the only remote gaming server worth using (Parsec) doesn't work on Linux.