Well I mean I've never heard anyone argue in favour of absolutely unlimited immigration but okay.

How do you measure culture empirically and how can you empirically say that culture is being balkanized specifically by immigrants and not other factors? You can't just take anecdotal evidence to say okay no more immigration because you have big feelings about it. There are places in the world still where having a non-zero amount of people of a different race moving into the neighbourhood would trigger some people to make the claim that the culture is becoming balkanized and sectarian.