Anything that isn't totally bland and flavourless when it comes to Rheinland ends up being equated with Nazism almost immediately. Every other corner of Discovery can get away with all kinds of imagery and lore-related atrocities simply because the real-world analogue for each of them wasn't involved in any (overt) real-world no-nos in the past century.
It's also a really handy buzzword for people to jump onto and bash immediately, because Nazis and Nazism are indefensible and it's a lot easier to pile on and whinge than it is to separate fact and fiction for one second.
tl;dr you're only allowed to play racist genocidal types if you're playing in Gallia or something; if you do anything remotely similar to that in Rheinland it automatically makes you a neo-Nazi. :thinking: