So I don't think xenophobia does conserve cultural identities as they are. They just conserve the notion of them existing, or the name of them, and perhaps loosely the home turf. But a quick look at all the Americans who call themselves 'Irish' and 'Italian' without ever having been anywhere near Italy or Ireland in several generations, shows that cultural identities can even survive a change of homeland, so that again makes the Jews' "achievement" seem a bit less 'special'.
TBH I think it's opposition that conserves cultural identities "as they were in the time of our fathers" sorta thing. "Italian" communities within the New World tend to behave in such a way and subscribe to values that, in Italy itself, are considered archaic and nowadays pretty rare. In the New World, the Italian immigrants felt their Italian-ness was threatened by the distance from Italy and/or the presence of people from other nations in close proximity, whilst in Italy itself the culture was considered 'safe and secure' as the dominant and official culture, and so the motivation to really pickle it and resist any change was far weaker.