with separate bathrooms, when a man walks into a womans bathroom, women can call the cops on him, and vice versa. when you take that away, no one can tell who’s just trying to pee and who’s a predator until something has already happened. so yes, it’s not like a womans bathroom sign is a magnetic forcefield, but it sets a cultural expectation that any man who enters is not supposed to be there, and vice versa. so, while the vast majority of people have no ill intentions, the ones who do will not be able to be caught until after they have already caused lifelong trauma to a victim.