Well, OK. I mean, sure, "all-girl" spaces can exclude anyone who is not unanimously agreed to be a woman.
Got body hair? Somebody says you're not a woman!
Strong jaw, Adam's apple? Somebody doubts your womanhood! Out!
Short hair, unpainted nails? Lack the hallmarks of femininity, so out!
Like sports? Can't cook? Unwomanly! Out you go!
And so on. What, the room's empty now? Your imaginary female ideal should thank us for protecting her from so many phonies.