One of the end goals of the radical feminist movement from the beginning is "not just the elimination of male privilege but of the sex distinction itself" (Shulamith Firestone, The Dialectic of Sex, 1970) so it makes sense that radical feminists would reject further entrenchment in social gender identity. That said, the movement has obviously been co-opted by transphobic bigots and other (better) feminism has progressed since the 70s.