Why do women post #saynotowhiteboys on twitter?

Iv seen many women make post about how they have had sexnwirh black men and will never have sex with white men again. Usually followed by hashtags like #snowbunny #bbc #teamblackguys and of course #saynotowhiteboys. Why is this allowed on Twitter when other racist tweets are taken off? Why do these women hate white men?
Why do women post #saynotowhiteboys on twitter?
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