That's not true. You get all the keybindings of Emacs in insert mode, and you get all the keybindings of vi in command mode. vi and vim are different enough that experienced vim users cannot use vi at all. I know, because I've invited them to try.

(Incidentally, mg is pretty easy to use as an Emacs users. The only odd thing is that ENT does not end an isearch, because mg thinks C-m and C-j are the same thing. What?)