Widely believed would be a better phrasing, as you may compare anywhere with low to no support for free speech and they will be more oppressive and violent than anywhere in say Europe or North America that has greater support for free speech, the correlation will be huge.
Then you could compare somewhere like the US with somewhere like France or Germany and ask if there is a greater amount of violence in either and see what could be attributed to speech. I doubt you'll be able to produce strong enough evidence for your position to then claim it as widely accepted over widely believed or just advocated for by parties that benefit from less freedom of speech.
Maybe you can, but I'd need to see it first.
Europe is one place with more limitations on "free" speech, and pretty much no parties or political grass-roots movements here are campaigning for any radical changes towards an American-style legislation. (Right-wing populist parties and movements in several countries are complaining about hate-speech legislation going too far -- and may even have a point -- but AIUI not even that means they're against the main idea that it's right to ban harmful speech; they just disagree on the definition and limits of what's "harmful" with regards to the kind of speech they want to indulge in.)
> Then you could compare somewhere like the US with somewhere like France or Germany and ask if there is a greater amount of violence in either and see what could be attributed to speech.
Crazy American lies freely spread under the guise of "Free speech!" gave you January 6.
And it absolutely is widely accepted if you look at democratically produced law across the world. Restrictions on harmful speech exist literally everywhere in democracies. It's what people vote for. It's absolutely widely accepted.