Tens of millions of poor, uneducated, unskilled, ignorant, proto socialist immigrants doesn’t help any economy. It hurts it badly and is a huge burden in Social security and welfare benefits.
If population increases helped the economy then why are so many third world countries that have high birth rates like Mexico complete economic disasters?
It is technology, innovation, entrepreneurship, free markets and automation that increases productivity and raises living standards. These uneducated immigrants stifle innovation, stifle automation and advancement of technology.
Japan doesn’t need to import millions of Mexicans . They build robots to work in their car factories. That hasn’t hurt the quality of their cars by the way.
Mass immigration helps to expand the economy but I would agree it's not necessarily beneficial when total costs are taken into account. Low-skilled immigration is primarily fueling the service industries, which require little skills and don't pay much while sticking taxpayers with all the social bills. I see no reason to base economic policy on that type of immigration and would prefer one of selective high skills instead, but not where the sole purpose is to drive down wages as the H-1B program does.
Politicians in DC for whatever reason are determined to import a massive poverty class that will come to haunt this country in the not-too-distant future.