Yeah, the Wikipedia page on 'fighting words' goes on to describe how the doctrine has since been limited. Shouting 'you are a fascist' at a cop probably wouldn't pass muster as unprotected speech these days (if you managed to make it to court alive and weren't preaching gibberish to a large crowd that was blocking traffic at the time.)

Still, speech isn't somehow inherently harmless or different from other actions that we take. It's bad to take someone's things with a knife, but I'd say that it's even worse to take someone's humanity with a word.