I guess I left out what I thought was a shared premise: immigration patterns in Europe are heavily skewed towards refugees and economic migrants. But yes you’re right that the kids of skilled immigrants can score very high (as you’d expect), I just think that’s not as relevant to Europe.

Indeed it would be nice that people not lump everything into "immigrants". There are different categories of immigrants. I think it is fair when someone makes a comment about immigrants that applies only to one category, to counter with a comment about immigrants that applies only to a totally different category.