Take Xterm, for example. I did benchmarks over remote systems long ago. When it came to performance over the network it was absolutely trounced by Gnome-Terminal. And Gnome-terminal was a lot slower then then it is now. The reason was because Gnome optimized text output on scrolling text that minimized the latency impact. And it still sucked.
There was a reason that it never saw widespread use in the enterprise outside of very nitch sysadmin users on pretty much local area networks.
Were as Windows has been used to support thousands of users in a single environment with almost entirely remote applications for a very very long time now. For most users and most applications there is no difference in functionality between remote and local applications.
Were as X11 will never be able to accomplish that unless the computer is sitting in the room next to you. Nomachine and similar tech can speed it up, but that isn't really X11 is it?
