In principle maybe, but all present implementations fall a bit short. Why can't I use my mouse to position the cursor in any shell? Placing the cursor with the mouse is something people commonly do in terminal editors like vim or emacs; the efficiency arguments against it fall flat because this is entirely optional and besides, many people use laptops with either a track-point directly in the middle of the home row keys or with a touchpad directly below the keyboard.
And there's no technical reason it couldn't be done; years ago I once did it as a proof of concept. It just hasn't made it into any major shell yet.. besides eshell anyway. It does work on eshell.
Anyway, it's not really a big deal, not important enough for me to pursue, but I do think it counts as a counterexample to disprove the "peak UX" claim. Command line interfaces in principle are great but in practice we're doing it by emulating hardware that went obsolete decades ago and piling cludges and hacks on top of that to make it feel a bit more modern.
Another example; there are a few ways to inline images in a terminal emulator but they're all kind of shit in their own ways; graphical thumbnails have clear utility when listing some directories; every serious file manager supports it but to do this in a terminal emulator is cludgy hacks.