Never forget, the Jews say of the Shoah. It becomes harder to keep that promise if it's seen as uncivil merely to draw comparisons to that era. And it's important that the promise be kept. One can accuse someone of an intolerance akin to Nazi supporters without accusing someone of wanting to re-enact the Shoah. And it's certainly reasonable to analogize contemporary attempts to level the 1% with the corollary attempts in Germany in the 1930s. That analogy is not the same as to depict Occupy sympathizers as Nazis. When it is taken that way it's likely simply an attempt to divert serious contemplation of the actual similarity between the motivations driving those two movements.