I think that there are times when women just want to be with women, no hate intended. Sometimes I just want to go out with the girls and talk girl stuff. I think that's where the "haters" come from. They saw this site as a place for women to openly talk because some people grew up being very open, some people grew up unable to truly open up when men are around. It's not your fault but it's not also their fault.
For example, I take a burlesque class and I love that men are not there. You feel comfortable and can open up more. I love my body more so now and can therefore be more confident. Legally, I'm sure if a man wanted to join, he'd be allowed to but in a sense by wanting to use his right to fairness, he takes away a level of comfort that he wants to force on us.
As a counter example, I don't believe a woman should be in the Boy Scouts. You can claim fairness all you want but there is something about the special bond dad is going to have with their sons if mom was not there.
I know that people want to "get with the times" but sometimes you can't change the dynamics of how men and women behave around each other. So, I actually don't mind in this group that men are here since the dynamics of family has changed but, for some women, it will take away a sense of openness and comfort and if "non-haters" are not willing to realize that then you are exercising a different kind of hate.