Shouldn’t it be obvious? How Mormon Women Hold and Exercise the Priesthood Today

If Mormon (LDS) women may be delegated priesthood authority, why are they not entrusted to make decisions or preside over mixed gender groups?  If women may exercise the priesthood to perform ordinances in the temple, why may they not do so in public?  If women may hold the priesthood without ordination, shouldn’t they be taught how to receive and use it?