Hypothetically, if you were a Machiavellian hiring manager:
You would also prefer a foreigner on a visa because they would have less freedom to leave the company than an equally paid employee who wasn't worried that quitting a job would risk being forced out of the country.
Also this would make the foreigner more worried about the consequences of being terminated for unsatisfactory performance.
It's hard to imagine this not being abused. Even in academia, where the H1B - green card process is pretty much a railroad. I've seen a department drag out the green card process over the span of years - out of fears that the professor in question might just jump ship and ditch the rat nest as soon as they get the green card (that was my best understanding of the situation).
Good point, and too nuanced for the article, alas.
Academic H1Bs are not transferable to commercial employers, so you're even more trapped than you'd otherwise be. The department I worked for at Stanford had a blanket policy not to sponsor green cards for staff. Ironically this policy made me leave earlier than I would have otherwise as I did not want to be left in limbo as I approached the 5 year H1B limit.
His words after joining Intel: "That was the first time I found out all these managers in US blatantly use h1b situation to make people work more than others".