The Nazis, like the Communists, were (and remain) pro-big government, pro-totalitarian, anti-individual and anti-private property.
Hitler literally abolished private property rights after the Reichstag fire. The only differences between Nazism and Marxism were national vs international, and having a different outgroup - a different selection of people to hate on and steal from. Jews or Kulaks.
You ask why, it’s simple. Even the Stupidest Left Liberal knows that Nazis are associated with something bad.
Sad part is THEY HAVE NO CLUE AS TO WHY. The Left only needs their Stupid minions to know Nazis are bad and anybody the Left says are Nazis are automatically bad.
Truth and Facts to the Left are MEANINGLESS.