> there’s _plenty_ of legal limits to free speech in the US

Not really? The limits are essentially directly inciting violence, directly threatening, and knowingly aiding someone in the commission of a crime (ie literally coaching someone else on how to break the law). That's not "plenty", that's really the bare minimum (and exactly how it should be, from my perspective at least).

Edit: Crap, just realized I forgot about our ridiculous obscenity limitations. Those shouldn't exist IMO, but to be fair about the only thing that's managed to run afoul of them so far is literal bestiality porn. (https://supreme.justia.com/cases/federal/us/413/15/) (https://caselaw.findlaw.com/us-supreme-court/535/234.html)

I don't think there should be any limitation on the right to freedom-of-speech except that strictly necessary to be compatible with other natural rights, like the right to your life. The classic ban on shouting "Fire!" in a crowded movie theater can be justified entirely on this ground, because that utterance may cause people to be trampled when people panic. It is not clear that libel laws can be defended on similar grounds, or such grounds at the very least would severely limit the reach of libel laws.