Steven is right. One Profile Manager can add and remove other Profile Managers.
This should be done rarely. As Tami notes, it's commonly done with the massively-merged profiles for deep ancestors, but not elsewhere.
A wiki is designed to give users a lot of power and control. An incredible amount, really. System restrictions are always carefully considered and done only when absolutely necessary.
If a couple users are abusing this power, it's better to fix those individual profiles and close the accounts of those users. (Steven, let Tami or me know if this is one of those cases.) If it gets out of control and more users are abusing the power than using it correctly, we may need to shut it down for everyone.