> low fidelity version of a browser UI?

That's the point. For me, with very few exceptions, modern web UI is steaming pile of dogshit - no consideration for user's attention, speed, or usability. TUI are extremely low fidelity; there's nowhere to hide all that enshitified cruft! Stripping the functionality down to its bare essence vs navigating a bespoke web UI with the design aesthetic of clown vomit. I can tell you which one is more productive for me.