In 1930, black people were the outgroup. Now we have a different outgroup.
In 2016 you get huge amounts of social approval points for opposing racism nowadays, so the victims of mob mentality will not be black people. Nowadays they might be drunken frat boys who raped the poor black girl, the community leader who's attracted vague allegations of some kind of misconduct, or the douchey smirking CEO who raised prices of a good consumed by sympathetic people.
Will you oppose the (now mostly internet, thankfully) mobs out for blood? Remember that get exactly zero social approval points for doing so.