@JoeBeam many immigrants come from places with poorly resourced education systems too. This take is true but it is also benchmarking the average population of the U.S. generally to the top of other countries’ talent. It doesn’t mean that the immigrants are better necessarily, just that the immigrants who want to come are at the top of their field in their society and probably globally too.
Even if U.S. education got better over time and things were fine, H1B immigrants still end up creating more jobs and increasing salaries especially as they become citizens shortly after.