This, this right here - and it's not just the US where this shows up (although it's definitely the most extreme). At the core, I think, it's all about "free speech": when you have a constitutional right to say whatever you want, without any limitations, you will first get a bunch of contrarians yelling all sorts of offensive stuff around "for the lulz"/"because they can", and eventually that sort of stuff gets normalized, and then societal cohesion (especially when the offensive stuff is directed towards minorities) and eventually society itself gets poisoned.
"The paradox of tolerance states that if a society is tolerant without limit, its ability to be tolerant is eventually ceased or destroyed by the intolerant. Karl Popper described it as the seemingly self-contradictory idea that in order to maintain a tolerant society, the society must retain the right to be intolerant of intolerance."