Don't they know that there is genres of anime and manga with pretty boys for women to oogle at as well?

These harridans define those away as male power fantasies. Yes, I've seen "Free!", the naked men and swimsuits yaoibait show, be defined as male power fantasy. Because their ideology DOES make sense, just not in any realm of objective logic: To them, anything that agrees with their ideology and makes them "right" is right and proper, and anything that doesn't is evil.