The "Hitler taboo"

Some time ago I watched a youtube video about someone infiltrating an American ultraconservative cult, using hidden cameras. At one point one of the cult members tells about knowing someone whose grandparents had been slaves, but who actually liked that position. It then shows the video creator making an expression to the camera (I think it was filmed afterwards) of the sort of "WTF dude, that's so messed up! That's such a racist thing to say!"

I don't know if that story is true or not, but I find it curious that in the modern (western) world there are certain things that you just can't say, even if they were true and factual. Such as, for example, claiming that some American slaves actually liked their position and didn't find it wrong nor oppressive.

This kind of claim just irks people in the wrong way, and usually causes a very strong reaction, that of outrage and disgust.

I don't know if this type of taboo has a name, but at least at this point I am naming it "the Hitler taboo" (a sort of allusion to "the Hitler card"). That's because the same thing applies to Adolf Hitler and the Nazi Party. In other words, you just can't say that Hitler, or the Nazi Party, did some good things too, or achieved some good things.

Or, at a very minimum, even if you were to say such a thing (which you are only allowed to say if it's a well established known fact) you must always, always, always add a "but" sentence after it. You can't just state something positive about Hitler and merely leave it like that. You must always ameliorate the taboo by either adding something dismissive about it, or telling something negative that nullifies the positive thing.

Preferably, especially in certain contexts (like Wikipedia), you should use the "sandwiching technique". In other words, even if you say something positive about it, you have to precede it with something negative and add something negative after it that nullifies the positive aspect. Heaven forbid someone gets the wrong idea!

I find it interesting how there exist these certain taboos in our modern western society which you either just outright cannot state out loud (without getting a strong reaction of outrage), or even if you were to do it you must never, ever state it on its own without any buts.