This is why we're all supposed to be all nuanced and shit when it comes to Communist atrocities, but when it's time for the Fascist atrocities everyone has to stand up and yell HITLER HITLER HITLER. Precisely like a five-year-old.
It's just a sort of national lookin' after #1. We naturally ignore the sins closest to us and focus on those of others. Left is "self" and right is "other." Otherwise, we would need to express genuine collective guilt rather than dime-a-dozen collective contempt.