It makes perfect sense that the most totemic example of evil in human history would get a lot more mentions than the various runners up. When we try to give examples of goodness, we evoke Mother Teresa and Gandhi, not sort-of-nice chaps.
What’s more, the totemic nature and frequent invoking of Nazism ensures that its firm status as the greatest evil ever is reinforced. Given the alarming rise of anti-Semitism in many parts of the world, the fact that there can be little doubt about polite society’s revulsion toward Nazism is reassuring.
And here’s another reason Nazi analogies aren’t always bad: Some things actually are like Nazism.
The 1938 Munich debacle really is an example of what happens when the civilized world puts cowardice ahead of principle, and a cautionary tale of the dangers — and immorality — of appeasement. Does that mean we need to let slip the dogs of war whenever a tinpot dictator blows his nose? Of course not. But Munich was not a sui generis event, and to a priori dismiss any comparison of any situation to Munich as faulty simply because it’s compared to Munich is ridiculous.