@julia X forwarding also used to be a lot more viable because X programs used to use X's server itself to do a lot more things. For instance, font-rendering was done X-server-side for a long time, and when the move to have font rendering happen client side started to happen, it was very controversial, though it turned out to be worth it. But things like that change over time...
I did run some older X11 applications with x11 forwarding over a LAN, that worked pretty well! Long time ago tho