With Europe, it's not immigration that's the issue. It's refugees. The problem with refugees is that the influx is sharp and intense and refugees aren't really part of the workforce nor can they speak the language. Getting them up to par language-wise is going to take a lot of effort (as opposed to illegal immigrants who already have language skills, but don't have legal labor protection thus are the most heavily exploited labor class).

Like, in China there's already a substantial amount of Vietnamese/Thai/Filipino illegal immigrants working the lowest paying jobs. It's part of how manufacturing is able to keep the cost low. Letting those guys get legal residence and have babies in China and putting those kids through the Chinese school system to generate more labor isn't going to really upset anything system-wise. Once those kids have been fully brainwashed (because let's be real, Chinese education is basically PUA), giving them a way to become "loyal Chinese" is a quick and easy way to expand the population without forcing people to make babies.