Among the ways that people with different cultures have managed to minimize frictions have been (1) mutual cultural accommodations, even while not amalgamating completely, and (2) living separately in their own enclaves. Both of these approaches are anathema to the multicultural cultists.
Expecting any group to adapt their lifestyles to the cultural values of the larger society around them is "cultural imperialism" according to the multicultural cult. And living in separate neighborhoods is considered to be so terrible that there are government-financed programs to take people from high-crime slums and put them in subsidized housing in middle-class neighborhoods.
Multiculturalists condemn people's objections to transplanting hoodlums, criminals and dysfunctional families into the midst of people who may have sacrificed for years to be able to escape from living among hoodlums, criminals and dysfunctional families.
The actual direct experience of the people who complain about the consequences of these social experiments is often dismissed as mere biased "perceptions" or "stereotypes," if not outright "racism." But some of the strongest complaints have come from middle-class blacks who have fled ghetto life, only to have the government transplant ghetto life back into their midst.
Thomas Sowell, “The Multicultural Cult”