[steveklabnik]

> then that's more about type compatilibity than about limiting the scope of memory aliasing in general.

It's about limiting the ability of pointers to alias. The C standard even has this parenthetical:

> The intent of this list is to specify those circumstances in which an object can or cannot be aliased.

You are correct that it's a pretty narrow set of rules. There are only six items on that list. But it's still an aliasing rule.