You're misusing the term. Sexism doesn't apply to forming groups based on common interests. Did you ever read the Dames's bio? They created the group for girls who just want to play with other girls due to the sexism that goes on with gaming currently. It doesn't mean they don't join in on other mixed groups it just means that there is an all girls clan they can hop into. There's all girl teams for nearly every sport out there, are they sexist? No. The Dames aren't either.