The mind is very complex. Trying to force it in one of 2 labels based on sexual activity can lead to unnecessary stress and self-loathing. Homosexuality is indeed stigmatized since the beginning of time and self preservation will coax someone to avoid being labeled as such if allowed to do so. I admit that there are those that fit this category, depending on where they are in their own self-acceptance. Sexuality, though, is too varied to be simply categorized as a straight or gay act. "I am a man and if I get fucked in the ass then I am gay whether I admit it or not." "I am a woman and if I eat pussy then I must be gay; therefore if it's impossible for me to be attracted to a man, and if I do so, I am denying my own sexuality." Yet there are men who likes to be pegged by a woman with a dildo, or by a trans woman with a dick. There are women who has had sexual encounters with another woman, and still identify as straight and ultimately prefers men. There are Bi men who equally likes to be with both men and women. I am not discounting that there are homosexual men who have not accepted their own sexuality because of societal norms and pressure, but I believe that is not always the case. And, If it is less traumatizing mentally for someone to participate in a sexual activity without being forced a label because of its societal implications, then so be it. I don't think it is necessary to define someone else's sexuality just because it fits nicely in a box. Perhaps it's the other way around, that if homosexuality wasn't condemned as much, more straight men would explore these sexual acts like women do, without being labeled.
(Please do not take this is an affront to anyone else's statement but a healthy discussion on the topic.)