Summary: This site is completely for profit and not for supporting any of the causes it claims to support
Because they encouraged kids to swear to forward an agenda they do not actively support - this is an advertising scam, to get you to pay $20 for a tshirt with an obnoxious and cliche phrase on them, when you could buy one from an actual charitable organisation who need the money to forward issues like homophobia, racism, ableism, and feminism.
And most importantly, charities fckh8 claims to support, do not want fckh8's donations. Not that fckh8 were actually planning to donate.
Stop supporting fckh8, they are simply making a profit off serious causes.
They made money off the LGBT movement
They made money off Ferguson
And now, they're making money off feminism.
And the sheer number of you buying shirts are actively enabling them to continue making money off the oppression of groups of people.