The point was the original question "you mean it can do more than is actually possible to do with a mouse?" was wrong because it isn't a question of mouse vs keyboard since mice are not meant to be used by themselves but instead they augment what you can already do with the keyboard.
There's a menu item for Undo in most GUI applictions. But who has time? If you can undo from TUI vim without a keystroke, I don't happen to know how.