Because nazis were peak of totalitarianism disguised as democracy and stemmed directly from seemingly (that is while looking at smaller parts of it) democratic process

Because it is what happens, and that's why the EU behaves the way it behaves. Sure, money, lobbies, and power are the usual suspects behind many decisions, but in this case (and Hungary falls in the same bucket) there is IMO something "purer" behind as well. But I might be naive.

I don't know if you noticed, but some things awfully similar to Nazism are currently popular again, worldwide. Mostly not popular enough to actually win elections in most cases, but enough that many people are thinking about how to stop almost-Nazis from winning elections, which of course gets the latter group labelled as almost-Nazis for trying to interfere with elections.

There are many groups with agendas to kill or expel gay people, trans people, Muslims, atheists, etc. It's sadly normal for those groups to exist; it's not normal for them to be anywhere close to power and we need to stop them getting power because we already know what happens if they get power. "All it takes for evil to triumph is for good men to do nothing" and all that.