Well, average population IQ certainly benefits when you don't import a bunch of dumbfucks, but genetically speaking our Asian cousins share a lot of the same selection pressures as Europeans and Neanderthal admixture, which feature a lot of IQ boosting genes, and culturally have rewarded IQ with their long standing emphasis on academic achievement, which helps push smart people towards other smart people and have smart babies, leading to a positive feedback loop.