Here’s why I hate the whole “men are only friends with women to have sex with them” idea—even if it’s true, which it shouldn’t be:
Because it reduces a woman’s value as a person to sex. You can’t possibly want to be friends with a woman because she’s funny, or she likes the same TV shows, or she gives you good advice about how to deal with your girlfriend, or she’s smart and interesting… No, you can only be interested in her as a sex object or nothing (or a relative, or a friend’s partner, in which you don’t have an option for sex and you can’t be nothing).
And pop culture feeds this narrative. In most movies, the only speaking parts for women are those who are already or will become love interests for one of the men. In TV shows, male and female partnerships are said to have “unresolved sexual tension” because they couldn’t possibly just be friends or colleagues. And nearly all narratives about a woman involve a romance, because a woman can’t exist without wanting to be in love (and yes, this is coming from someone who intends to write romance, because it’s what I like; but that doesn’t mean I don’t want to see some narratives without it, even if I don’t like them as much personally).
This creates in society the expectation that a woman who is not in a relationship must want to be in one. That she can’t possibly exist without desiring love or sex. That being a sexual partner, girlfriend, or wife is her primary purpose (she can have other purposes, but she’ll always be strange for not having that one).
Because, at the deep and unknown core of the above sentiments, is the idea that all a woman is, her primary purpose, is to be a sex object for others (you can romanticize it by saying “romantic partner,” I suppose).
She is a sex object, a potential sexual partner, or she is nothing.
Why else would anyone want to be friends with a woman, right?