Liberals love multiculturalism. It lets them feel merciful, and forces unfortunates to endure sacrifice for the general progress of society.
If unfortunates stand up for themselves, liberals can play dumb and call unfortunates selfish racists.
Besides, liberals really aren't socialists. They enjoy exploiting multiculturalism in order to expand the labor supply and drive down wages to do menial jobs. This even applies to Israel which hires Palestinian migrant workers in the Middle East where recent embassy attacks happened. Israel's American Jewish relatives also vote 75% Democratic, endorsing the multicultural agenda.
Multiculturalism also lets liberals be elitists in not having to preserve native family values. Instead, social decay creates the self-fulfilling prophecy of demanding social services. This professionalization of reform gives liberals fancy jobs to do so they don't get dirt underneath their nails.