It's about _carrying capacity_, not "infrastructure". We can only absorb people at some maximum rate and still have a chance of bringing them on board with hard-fought Canadian cultural values, getting them up to speed with our official languages, and integrating them into local communities. Past that rate, the tendency is for newcomers to seek out people who are from their home country and speak their language. This creates insular bubbles of culture and damages any effort to actually create a cohesive whole.

Multiculturalism in Canada is different than in America. Here, there's something bigger for us to assimilate to that actually still holds value as a construct; a greater Canadian archetype that has done extremely well as a common point for newcomers to converge on for the past few decades. However, it would be easy to exceed the rate at which this is workable, and end up with a fractured country where people retain their entire original identity and never "become Canadian". This is a legitimate concern for people that love the country created by people who are Canadian through and through and want to see some of our lesser-known values (such as anticorruption, engineering quality, sustainability, etc) continue to propagate.