> All of those create demand that adds up to substantially more than one job (about 1.2, to be exact [1]).

So, what would an opponent in good faith say against that? Is this a well known thing among Real Economists, which is just brushed under the rug when a politician wants to appeal to people with an anti-immigration policy? Or is there more to it?

It seems to be really low hanging fruit to explain that and have massive economic boons by increasing immigration, right? Or is that not the conclusion? Because what you said is really intuitive and some politician should be able to just easily use that. Why don't Clinton/Obama say that when explaining why they're letting illegal immigrants stay?