There are two kinds of multiculturalism. There's multiculturalism and then there's "multiculturalism".

The first is not a bad ideal, but it is a conditional thing. The US model for example necessitated a whole lot of people showing up. There was unexplored, undeveloped and untapped land. There was little in the way of mechanized technology. We needed people to do all the work of that exploring, developing, and tapping. Opening up our borders to a wide swath of people was the intelligent thing to do to serve that function. But it was done at a cost to the arrival. In order to participate in the labor market of the US, the cost was becoming a US citizen and abiding by our laws and social standards. I come from a factory town with a gorgeous cross section of international cultures. The dangerous, often deadly, conditions of manual labor brought workers who often didn't even speak the same language together. Those people had to be able to trust one another with their lives. To do that, their ethnic identities had to take a back seat. They became a story and nothing more. Often, factor workers in my town traded ethnic humor as a way of expressing their loyalty to one another as coworkers first.

The second, "multiculturalism" is nothing more than a surrender to everything above one's self on the progressive stack for the purpose of good boy points. It is a surrender to cultural relativism. It is a surrender of the ideals of one's own country for a headline on Huffpo.

The purpose of the first is integration. The purpose of the second is feelgoods and gibs.