Why can't the 'main' keymap be an alias from 'vicmd'

[first name <33facebook@xxxxxxxxx>]

 <zsh-users-sc.1291846382.mkdokibkckoflkocimkl-33facebook><http://gmail.com/>

The following is from the zshzle page:

		  "Note  that  while `bindkey -A newmap main' will work when newmap
		  is emacs or viins, it will not work for vicmd, as switching from
		  vi insert to command mode becomes impossible."

Well, trying it by aliasing main to vicmd, i.e. `bindkey -A vicmd
main', i was "able" to to switch to vicmd mode, but the actual thing
that was impossible, is switching to insert mode.

now why?

I mean, why is it possible to have 'main' linked to viins and have
<esc> bound to the 'vi-cmd' widget, and not have the main linked to
vicmd while `i' and `a' bound to the 'vi-insert' widget?

cheers