Because literally all women HAVE been discriminated against, marginalized, sexualized, assaulted, and bothered by men. That's how I can say that. It's not an assumption. It's a fact. The CDC says 1 in 3 women are raped, 85% have been sexually harassed starting in childhood. With very, very few exceptions, all women have many, many first hand experiences with ill treatment at the hands of a man or men and patriarchal culture. Fifty years ago women were second class citizens under the law, and although the legal aspect has changed (although women still too often have to sue to get their rights upheld - and things like unequal pay for equal work still take place, even though it's illegal) the attitudes that accompanied that sort of patriarchal society have not been erased from the collective unconscious.

Anti-semites and KKK members are people from dominant demographics bothered by the fact that these "lesser" people want equality. They haven't been "mistreated" by anyone because the one holding the social power cannot be "victimized" by the demographic holding less. Hellooo.... Duh!