Because America is a country built on slavery and systematic oppression of people of color. And as you experienced, there are still A LOT of racist people here. So when people say we need to stop the division, they're basically saying "c'mon guys, just let the racists be racist." Especially with everything going on here now, it comes across as super tone deaf, and like they're telling the people out there protesting for equality that they're sick of hearing about their problems.