I was in IT for nearly 20 years. Indian headhunter companies are a huge problem. Both Republican and Democratic organizations have found significant fraud issues with them. There are a few "advantages", as a company might see them.
One lower pay, which may or may not play a role at that level. Two, it's much more difficult and dangerous for them to switch jobs before they at least get a green card (which if memory serves can be from 5 (very low) to 10 years in the making) They can be easily deported (refused visa renewal) during that time. So they basically can't and won't complain about long hours or calls 24/7. Of course, they normally start as contract which means zero benefits from the company then they might be hired after 5-7 years; and only then start accumulating time to exceed that standard two weeks PTO. The last one, I can think of offhand, is that also because of fear of losing their visa, they are often "yes" men/people. As, in can we do X in two weeks. If it doesn't materialize tends to be finger pointing to people or foreseeable factors. If it does get "completed", it's often buggy but, again Execs get their buy in and can point fingers down, if not satisfactory.
H1-B was "specifically" not meant to replace American workers with cheaper foreign labor, but that it's exactly what it has done for many, many years. There was a minimum pay set in 1989 of 60K, which has never been raised (Bi-Partisan attempts were made but those were buried in subcommittee never to receive a vote). H1-B has indirectly subsidized businesses paying for it by displacing american workers through giving away citizenship. It's that simple. If you've only had one IT job, and/or aren't in the industry, you may not know but I've both been replaced when an Indian firm took over all IT in a company and I've worked for one of the headhunter companies. I've seen fraud, the breaking of security laws (federal), more than once. People that ignore the issues with H1-B don't seem care about American's losing jobs and/or careers, benefits, job stability. If someone claims to support diversity, H1-B overrides any and all American's; so you can forget about Black, Latino, Women, in IT.
To clarify, I'm not Immigrant, but H1-B went from something to subsidize American companies with "Highly Skilled" workers that we didn't have in the U.S. to a replace American's and lower benefits. It has made IT the lead in professional gig-work. Also, I don't claim to know about any other field. I don't know if there are Indian headhunter companies in other industries that companies contract with.
Lastly, if you are young, I would advise against IT as a carrier. Unless/Until those Indian headhunter companies are no longer a factor, it's a sure way to low pay, low benefits, and long hours, calls and text when your off work (vacation and middle of the night included), and almost zero job stability