The idea behind such a ban came from the experience of the fall of the Republic of Weimar in Germany and the rise of the Nazis. It was the experience that a state can be destabilized and can fail. And hate speech and propaganda obviously played a very important role. Stuff like that for example:



In reality, such laws a rather symbolic, though. It's obviously more difficult for Nazis and other scum to promote their causes. But even these fucks are usually clever enough to find loopholes.