MIDX Schema Question

I’m wondering why the modUserProfile’s “User” alias is an aggregate alias. If you delete a user profile, the user remains in the DB, and you have a user with no profile (and no email address).

The modUser object’s “Profile” alias is an aggregate alias, so if you remove the user, the profile is also removed.

Shouldn’t they both be composite aliases? I understand that the User is the primary object, but all users are expected to have a profile.