I have been to Vancouver recently, and made a point of loo0king for those "ghettos", and didn't find them. Vancouver looked much less diverse than Montreal. It looked very white, with a substantial Asian presence, but not overwhelming.

I saw few black people, and fewer than a handful of hijabs. Montreal is a lot more "diverse", and "visible minorities" a lot more visible.

The idea that there is no ROC mainstream culture is wrong, it is just so overwhelming people who live in it take it for granted and don't see it. Outsiders do.

Most immigrants know very well the mainstream culture is Anglo, and the younger ones learn English, they cannot get far in America or the world without it.