> Even during World War II, the Allied powers went to war against Hitler's expansionism, and not on account of the holocaust. If Hitler had just concentrated on killing people in his own country (like Stalin), no one would have clamored for bringing the Nazis to justice.

Not sure if we can say that. There were reports of what's going on smuggled out of Nazi territory, but they were mostly ignored; public opinion learned about the genocide only when Allied soldiers stumbled upon the concentration camps in 1944. Hard to tell what would have happened if people listened to the reports that came even before the war.