Does it really bother you that people care about their heritage? US culture is a culture that assimilates, people remember where they come from. It's almost mean-spirited that yall fault them for this. Better than forgetting. I remember where my ancestors came from because they came here from somewhere they were not wanted.

What I would ask you is why does it irk you, why do you care? Is it some hindance to my culture that I want to learn about it and try to "cosplay"? What would you prefer that we act as though we're here sui generis? Is somebody's culture lesser because they're not in that country at that time?

People of Italian ancestry in the US did not forget everything about their past, in many cultures that transition is even more recent; I remember my immigrant grandmother. Comes off as gatekeeping people who would otherwise be your relatives.