"If a woman came here and said her boyfriend of 36 had no assets and wanted a child with her and was then going to work part time as long as she married him and gave her half ownership of her mortgage free home, people would tell her to not to do it. They would call him all sorts."
There's always one, isn't there?
The difference is that a man can create children with hardly any effort or risk on his part. When a woman has children, she takes a much bigger risk and her entire body is involved, for a really long time. She can even die in childbirth, a risk that the sperm-provider doesn't have. This risk and burden from the bearing of the couple's children by a woman, merits support where a man's much smaller contribution to childbearing does not.
Likewise, a SAHM usually does a lot of childcare work. If she didn't do it then it would have to be paid for. Lots of women dial back their careers to allow the man to enjoy HIS career growing apace. Why should she get shafted by this while only he benefits? Men who are the subject of mumsnet threads about leeching off of their female partners, are described that way because they expect to be supported and ALSO do not take care of the children, leaving the woman to do it all.
Men who abandon their partner after having children aren't given the same negative social pressure as are women. They are just noncustodial dads. Women who leave their children to be raised by a male partner are seen and treated in a much more negative light. It's just a lot easier for a man to leave the expensive burden of childcare to the woman and look after himself, than for a woman to do the same.
That said, yes, it's on women to value ourselves enough to abstain from providing children and housekeeping and intimacy, without receiving the security of marriage in return.