Earlier quoted context omitted.
For terminal server use cases, there are things like VNC, SPICE, NX, etc. The X11/ssh thing is for when you want to run a mix of local and remote applications on a single desktop, which i think is pretty unusual these days.
Is it really that unusual to do some data reduction/analysis on a beefy dedicated machine and wanting to look at the results right away using the same terminal instead of having to copy the result files or using a shared network file system? Even more important if it involves any graphical interactions. Sure, one could use a remote desktop to do same thing, but it's a bit annoying if all you want is one window from t…
You should try xrdp. It can work like X forwarding (single application window forwarding), but you can also attach or detach from a running application (like screen or tmux for X).