Why should immigration policy filter out immigrants? One of the pushes behind Arizona's economic boom in the 90s and 00s was the influx of immigrant labor (who

Why should immigration policy filter out immigrants? One of the pushes behind Arizona's economic boom in the 90s and 00s was the influx of immigrant labor (who then bought houses that needed to be built/bought services that needed to be provided, and paid taxes for the government to hire more people to build/do more things). Immigration policy shouldn't support non-free labor, but it's unclear why we should only be focusing on the "best" immigrants, rather than trying to let in as many people as possible who will help build their communities.