I don't have a macro-level answer for you but an interesting anecdote: we opened a job for a Software Designer and looked at the first 9 applicants. All of them were in need of H-1B sponsorship, most were Indian, and most were "software-engineers-turned-designers". So at a micro (company) level, we hire immigrants because those are the candidates we receive.

Note: One of my parents is an Indian immigrant. I have worked with many great Indian engineers and many not-so-great, just like every other nationality.