You're not entirely wrong, but it's worth clarifying that chess tournaments aren't segregated in the sense of having a men's league and a women's league; most tournaments are open to anyone who can qualify. In practice, however, most of these open events are still overwhelmingly male-dominated, and that's a self-reinforcing tendency because a community where 19 out of 20 people are men tends to be pretty unwelcoming to anyone who isn't. The women's tournaments exist to give women a place to play where they don't have to deal with that. It's not ideal, but I'm not sure there's a good alternative - the demographic bias isn't something we can just decide to end.