There is a huge difference between natural cosmopolitanism, which most are OK with and the political strategy of top down enforced multiculturalism/mass immigration.
I think the basic problem is that people don't want culture changing levels of immigration, but mass immigration is being done with precisely that in mind. I don't know anyone who asked for multiculturalism, it was forced on us by underhanded means and our concerns were shouted down. It is clearly a planned strategy. It started as "just an experiment in multiculturalism". Who was it that decided that this experiment was necessary and why? As each lie supporting mass immigration from disparate cultures is exposed as just that, a new lie is promoted.