It's for the same reason we split any contest by gender: so women can win it.
Chess has a whole separate WxM category so while if they're really good at chess they can become a real GM, but there's also an easier category called WGM (Woman Grandmaster). Same for IM, FM, and CM - they're just as open to women as to men, but they still have easier equivalents called WIM, WFM, and WCM.
Chess has a whole separate WxM category so while if they're really good at chess they can become a real GM, but there's also an easier category called WGM (Woman Grandmaster). Same for IM, FM, and CM - they're just as open to women as to men, but they still have easier equivalents called WIM, WFM, and WCM.