In a way they are as there is no "men only" tournaments. There is open for all, and a few women only. You just won't see any women in the open for all tournaments as they fail to qualify so ending the womens tournaments would just result in having no female competitors at all.

They do that, in the men's division. The men's division is open. Anyone can participate.

There are 16 times as many male chess players than women so men dominate the open category by sheer number alone, it's basic statistics.

As such the woman's category is not so much a separate thing but a subset of the open one and if nothing else it provides visibility and a competitive field where women can deal with female instead of male asshole competitors so they can comfortably be catty queen bees instead of learning how to chest thumb.

Do you think that activities that are dominated by a certain gender are that way "naturally", or would you maybe agree that societal factors and sexism play a role too? The idea of "just leave things alone and let people do what they want" often ignores the subtle way that men and women are encouraged towards or discouraged away from those activities.

Then you will get all the top tournaments with maybe a few women, none of them will likely win (based on current ranking), which will cause possibly even less women to try chess and reinforce the vicious circle (less win also equals less money, less sponsors). Basically, after that you will get protests as well.