Even if we cede this point, the question is "do we want them" and "can we afford them".
The US military will not accept anyone with less than an 83 IQ. Many of our newest immigrants come from nations where the national average IQ is below 83. Some of the nations where the newest immigrants are coming from have average IQs that are clinically described as mildly retarded. I think the Military's minimum intellectual standards would be a good representation of the minimum IQ required to contribute valuably to our broader society whether a brick layer, electrician, or plumber as well. It's a good bellwether.
We have 5% unemployment, rampant welfare programs being overrun by US citizens, and we have our own health and wellness challenges amongst US citizens. We cannot take in any more people from the "common man" ranks, we need to first be loyal to our US Citizen "common men". Work has to pay to get the bums off their couches. Why is it so important to get our citizens off the dole? Because the dole costs about 6x to 10x more to the taxpayer than the 1x in benefit received by the recipient. Lowering the unemployment from 5% to 1% using US citizen labor will lower our tax obligations astronomically, PLUS we get the useful labors of the now employed citizens.
In order for someone to come to America, they need to be exceptional (e.g. 120 IQ or better), have a very important skill (e.g. specialty medicine, STEM, skilled trade). That's the only way our society gets a net-benefit from newly introduced labor that at some level is denying employment to an American citizen.
I can't believe that it is scandalous to say we need to take care of our own citizens first and that we shouldn't% o allow immigration of peoples that are below-median IQ.