As a proud Polish-American — second generation — I call “bull” on this.
I suspect what we’re dealing with here is the NYT’s standards of political correctness.
In this case: Avoid any appearance of picking on people of color by lumping some European immigrants in among the unassimilable foreigners.
Painful as this may sound to my fellow conservatives, any Third World immigration is bad for what historically has been a white, Christian nation. Some cultures are just going to have a hard time mixing with ours.
It was hard enough assimilating the Irish, Italian, and other Catholics into a Protestant culture. The fact that they were is testament to the resilience of that culture.
But our culture is like a balloon — it can only stretch so far before it pops.
And that’s about where we find ourselves today.
I'd say the fact that they were Catholic was more of a prejudice on the part of Protestants, and that they were assimilated because they wanted to be Americans, not Irish, Italian, or whatever, but Americans.
Anecdotally I know this is not true of certain newer immigrant communities, as workers come over here, live 10-20 in a multifamily, and ship their money back to their relatives elsewhere. They want to come here, make money, and then return to their native country.
Therein lies the difference between then and now.
As I mentioned above, there was a sizable migration of Poles to the US in the 90s but it was highly regionalized. Some are going home, but not to the extent that Irish immigrants flew home when the Irish economy boomed.