The interesting thing is that end result seems to be a proliferation of extreme views in the US vs other similar countries, which is arguably the opposite of what you might reasonably expect from the opportunity to allow freer discussion of ideas.
FWIW, neo-Nazi marches in Europe have way more people attending them than anything that American fash have tried to cobble up to date (including the particularly infamous one in Charlottesville). Radical nationalist parties seem rather popular in Europe lately as well, to the point where they already run some countries (Hungary, Poland).
Interesting, though not necessarily indicative of anything in its own right. I'd always expect a culture of free expression of ideas and a willingness to discuss fringe viewpoints would help reduce the proliferation of violent or socially destabilising behaviour, but I'm less convinced the degree of constitutionality guaranteed free speech matters all that much.
Is that the case, though? The US has problems of religious and political extremism, but is Muslim violence worse in magnitude than in France with its restrictions on religious expression, or anti‐semitism than in the European countries that ban Holocaust denial?
Most channels not restricted by those rules (subscription cable & satellite) set in-house standards on content for commercial reasons. And of the broadcasters that are covered by the regulation, they are the old stodgy networks and never choose to get near the boundaries.