The slavery-like dynamics of the immigration system is a surprising mismatch, versus the typical American business culture.
For comparison, I've spent time in a few countries where a slavery-like relationship with employers is completely expected and even supported by the employees. (Culture shock!) They imagine that it's the only way that businesses can function.
This isn't the type of business culture you want to live in, no matter the perceived benefits.
H1B is basically how big companies remain 'leen' enough to compete with start-up. This is made very clear in Amazon and PayPal India offices afaik, but sounds reasonable enough to be generalized. It is impossible for a large company with thousands of employees to remain competitive without the crunch-culture of startups. So they get H1Bs.
For comparison, I've spent time in a few countries where a slavery-like relationship with employers is completely expected and even supported by the employees. (Culture shock!) They imagine that it's the only way that businesses can function.
This isn't the type of business culture you want to live in, no matter the perceived benefits.