A plausible suggestion for Saami:
If the game sees that a vanilla menu is empty it ditches that menu display
This means a modder could knowingly empty a vanilla menu to free it up. If a beginning modder (or one debugging) left item(s) in the menu it would still show up.
This gives large mod makers, like myself and others, a new way to work with the menu system with that safeguard against some of the hiccups that can happen.