Feminist answer: Because men are misogynists. Actual answer: Because men respect women. That answer might sound completely nonsensical at first, but let me explain. (Also, I'm not saying that there exist no men who don't want women in their playgroups because of very sexist reasons. Of course there are. However, I'd argue that those are a minority. In the majority of cases where this happens, the reason is rather different, which I'll explain below.) Think of it what you want, but on average men's psychology is different from women's. Men do not get easily offended, and are rather stoic. When men who are close friends are engaged in a hobby, they often like to trashtalk. This trashtalk may sometimes even sound highly offensive and insulting to an outsider. Some of it might even be technically speaking "sexist", even though the men aren't actually sexist in the least. That's just trashtalk. And that's just how men's brains work. ...