yes this is what those idiots miss, is that "banning immigration" doesn't equal zero immigrant labor. It just means the immigrant labor is illegal, accepts terrible conditions and pay and will be deported the moment they make any trouble, ask for a raise, attempt to unionize or are no longer needed.

This means it will drive down total wages and conditions for the average worker even further than widely legalized and protected immigration, which at least has the floor of minimum wage + payroll tax + basic benefits + worker/labor protections from regulators (in theory). Without that floor, their wages and conditions will deteriorate even more rapidly.

Just like the existence of a slave class in the early USA made life worse for free workers, this does the same thing. Now you are competing against slaves and people making $1/hour instead of other workers that you can unionize with.