“Yep, American Communists were Protesting the War until Hitler invaded Russia and they Changed their signs on the spot!!”
For the longest time I tried very hard to figure out why Hitler hated the USSR with such a strong hatred and why the USSR joined the allies. I just could not wrap my mind around why tyrannies would be at war with each other instead of joining forces to defeat liberty.
Then I realized I was wasting valuable resources that I need today to fight the tyrants in my era and I gave up on the thought exercise.
Why do the Bloods hate the Crips?
The answer is simple friend= Power. Simply that. Power.
Because there is more to a political ideology than whether it is libertarian or authoritarian. For example, you can have two authoritarian governments, one of which requires everyone to be an atheist (Communism), another that requires everyone to belong to a state-sponsored religion (Islamism). Even though both are authoritarian or totalitarian, obviously, an atheist dictatorship isn't going to get along with a religious fundamentalist dictatorship in the long run.
Along the same lines, in spite of the fact that Stalin's USSR and Hitler's Germany used many of the same methods, their goals were opposite. National Socialism was nationalistic and rooted in social Darwinism, Communism (at least in theory) was anti-nationalistic and egalitarian. Communism was driven by class warfare - all private property was confiscated or abolished in the USSR. The Nazis, at least in theory, allowed powerful industrialists, bankers, and the aristocracy to maintain their property and wealth, and in fact saw differences in wealth and property as part of the natural order that they wanted to maintain.
So as far as the Nazis and Communists were concerned, the fact that they both had totalitarian systems of government was incidental, what mattered was that they tried to implement opposite worldviews with totalitarianism.