Granting Create/Edit permission to a specific user to the st

Granting Create/Edit permission to a specific user to the standard USER object. I did this to allow one user to act as the point person to create user IDs. I don't to grant him the SYSTEM ADMIN role because of business rules. However when I created a new user id, the Role field is not editable. Must the system allow this user already to create new ID and assign a role for this matter as I have already given him the access to Create/Edit the USER object? Without the access to assign a role, this ability to set permission (Create/Edit) to the USER object does not serve its full purpose.