Because none of that affected American history, dumbass.
Most people only talk about black slavery because that's the only type of slavery that was in the US.
Slavery is slavery.
Slavery is bad.
No need to make it a competition.
I think the reason people think that, is because there were 10 times the amount of black slaves sold than white slaves.
Not saying it's alright to blame an entire race for one thing, but that's why people think that.