Agreed, but what "prevents" it is that making a good keyboard-driven UI takes a lot of taste, extra effort to build it, and it must be revisited any time the UI changes. It's duplicated work. Ideally all GUIs/TUIs are usable with keyboard and mouse independently. A good example of this is when you have a fancy keyboard-driven workflow yet you can't even do the most trivial task without placing two hands on your keybo…
> extra effort to build it Also extra effort to use it. This is why we have the “how do I exit vim?” meme. A good user interface needs escape hatches so users can keep their head above water while they learn to swim. Most of what people want when they say keyboard-driven is closer to a cockpit (requires expert knowledge) than a general purpose UI.
How to exit is literally the second thing `vimtutor` teaches you, after hjkl cursor movement.