That would make sense if communities are indeed isolated and want to stay as such. To continue with our little analogy: while Tuscany (and a few other places) have this peculiar cultural trait, it's as still home for a lot of people who don't recognize themselves in that and they also belong there and need to be respected. Very often that's even the numeric majority of people.

"my grandfather and my father and I all cursed God for breakfast for three generations and now I suddenly have to talk like what this pope-kissing bigots want me to?" ignores that there are pope-kissing bigots in your society, your neighbor may be one, your friendly policemen may be well one, the old man across the street.

But also, there are people who are not pope-kissing bigots and YET behave themselves in a way to not saw division. Your children's school teacher may be one, perhaps cursing in the privacy of her home but giving you a look you if your children talk like little fallen angels.

We're all used to norms. I don't think that's the root cause of us having this conversation in the first place.

There is a group of people who is feeling their position in society has changed under their feet and they are frustrated about that. For them these topics become an identity-glue, something to hold on and to tell their ingroup from outgroups.

But there are also people who just don't like norms and just by coincidence happen to be aligned with whoever is the norm-breaker du jour.