Apologies, I'll be less nuanced for you. Hitler would have got nowhere if he was mute.
And these things were also drummed up by years (or centuries) of propaganda.
You don't see too many people bringing Leopold II.. Except for a recent article which made me go "Yay ! Finally !"
I believe that while the standard currently used by US courts (http://en.wikipedia.org/wiki/Imminent_lawless_action) is not ideal in all circumstances, it is largely functional and has not caused a great deal of harm. In practice, the way it plays out is that it gives hate groups enough rope to hang themselves in the court of public opinion. See: The WBC.