> X11 has a huge number of issues when it comes to network transparency. tl;dr is: it's not designed for this
X is very much designed for network transparency. The modern extensions that sling around pixmaps for every little graphical operation are what isn't. I can still remotely run X11R5 clients thanks to X and its network support.
You can, if by "network" you mean low latency LAN. Modern network remoting protocols work over high latency WANs as well, which X11 fundamentally can't do because too much of the protocol requires synchronous round-trips.
You can run X over a WAN with the eyecandy turned off. It could be run over a slow modem. The problem lies in everything that was tacked on assuming it would only be used locally.
X is very much designed for network transparency. The modern extensions that sling around pixmaps for every little graphical operation are what isn't. I can still remotely run X11R5 clients thanks to X and its network support.