The Nazis weren't criminals, they followed the rules exquisitely. It's just that they used their politics to put themselves in positions to change the rules.

It also is important, if we're to learn from history, to know that the nazis were favored for their conservative (right-wing) economics and their pro-worker (left-wing) rhetoric, but their actions were mostly defined by their fascism (a far right-wing economic and social philosophy).

Ignoring this is a great way to create a blind-spot that treats any group with fascist tendencies as perfectly safe as long as they're not actively doing a genocide yet.

On the other hand, i do understand and agree with what you're saying to some degree: the Left/Right divide is mostly rhetoric of divisiveness and quickly becomes a shorthand for "people with morally correct beliefs (people who agree with every single political belief I have and whom i will uncritically adopt more political stances from)" and "people with morally evil beliefs (people who disagree with every single one of my political beliefs and whom i will uncritically adopt the opposite stances of)."

This too creates a blindspot where people just assume their chosen team is incapable of morally heinous acts and will also ignore historical fact in order to maintain that dissonance, incidentally recreating the conditions that allow such abusers to rise to positions of power.