In my opinion, it stems directly from the concept of traditional gender roles.
Men are physically stronger and therefore perceived as the "better" sex. Women are physically weaker and therefore perceived as the "worse" sex. The general concept of masculinity is that a male is independent and has control over other, physically weaker than him, people - so women, and his children. According to this concept, no male other than his child should come under another male's control as they are supposed to be independent males like other. Therefore, a man who bottoms, as in is being penetrated, is considered to be taking the role of a woman in a homosexual relation, which deprives him from his manhood and makes him "the woman".
I think it's utterly stupid, but that seems to be the logic of most people. It isn't the universal truth, obviously but don't
some bottoms like to "take the role of a woman" by being taken care by a stronger male than them? Explaining the whole
daddy thing?
