Don't get me wrong, I'd be quite interested in a vintage computing discussion on the evolution of VT-100/220 etc terminal protocols. There were some interesting things done into the 90s. That's actually what I clicked in expecting. Of course, those were all supplanted by either XWindows (which I never got to use much) or eventually HTML/CSS. And if we're talking more broadly about structured page description languages, there's no shortage of alternatives from NAPLPS to Display Postscript.
It so happens that right now one is synonymous with the other but there's no instrinsic requirement.
There's probably something to be said for the inherent constraints imposed by the terminal protocol, but, again, we can build the same things without that.