Counterpoint: my parents came to the US when I was a child and they have none of those things. Their family ties weren't strong enough to last. Their ties to family back home deteriorated. There is no diaspora of extended family in other cities. Their own relationship was toxic and abusive, and they divorced. They are now living out old age alienated, isolated, and alone. They're not rare, they're just not nearly as vocal as the "my big, fat Greek wedding"-type people.