When people cite the benefits of mass immigration, eg, "where are all the nurses going to come from it we don't import workers?". I'd argue what they're actually saying here is, "if we don't create a migrant underclass who is going to work for the crappy pay we give nurses?". The only reason we need migrant workers to fill these roles is that they don't pay attractively enough for natives to apply to them.

The main benefits of immigration on a native population is that you create a migrant underclass. So if that's what we seem to want then our current immigration system could be improved. That's really all I argue.