I understand why you feel the way you do bluebeard. I remember once being really appalled at something a male poster said on a thread about childbirth trauma. It reminded me that MN is not a safe space and that it is open to everyone and anyone.
After another incident involving a couple of male posters, I had some of my posts deleted as I didn't want any Tom, Dick or Harry being able to do an advanced search on me and read personal things that are very much female issues. And I don't even share much personal stuff on here! (Certianly less and less).
I think one of the best things about MN is that it is a predominately female space in a world dominated by men. Apart from actual closed/private spaces and the odd feminist space on the internet, it is very very rare for the female voice to be dominant.
Of course not all women are nice and not all men are nasty - it isn't about that.
It is about socialization (as mentioned by Grennie) and perspective.
A female perspective on something like birth trauma is not going to be the same as a male perspective. Same for all manner of gendered issues such as DV, sexual violence, infant feeding and all manner of parenting and life experiences.
Of course MN is a public site and anyone is welcome. Of course there are fab male posters. Of course there are unfab female posters.
But MN as a rare thing, a predominantly female space, is distinctive and precious. I think it is good that it is called Mumsnet not Parentsnet as I suspect that it would change the tone of the whole place. I think a lot of what makes MN fun, plain speaking, witty, hilarious, so supportive and appealing to women is because it is dominated by women and it makes us feel a bit free.