I grew up and chose to remain in the US, and I have never seriously questioned the American norm around speech, but if I lived in a society that never had such a norm, I imagine I would regard the advocates for introducing such a norm into my society to have the burden of proof that doing so would be worth it.

I respect the advocates who make a consequentialist argument for the norm, but not the advocates that say that free speech is a natural right or a God-given right and believe that that settles the question.