I always thought to myself that terminals where just an easy to deploy cross platform ui. No other real reason to be using a CLI. Electron is another tool that rose out of being cross platform.
Compared to light-weight graphics (think early X programs), are TUI really that much more performant?
I understand they ARE now light-weight, portable and (relatively) simple.
I don't think they're much more performant than a GUI created with performance in mind. I think they're almost by default more performant with the lowest effort/lazy approach?
TUIs can be composable as well but you are 100% correct that I overstated the case.
I think you're actually right about terminals, per se. The path dependant complexity of standards (and lack there of) on the web seems spiritually similar to terminfo.
The step to CLI, however, doesn't seem well supported. I think the conversational interface has a lot of benefits beyond "easy to make it work in a terminal", although how applicable those benefits are to a particular task varies, as does how well those benefits are actually served by a particular system.