I've seen H1B essentially lock up some of the brightest people I've worked with... for years. Even a decade or so. You have to get sponsored, and you can't leave your corporate home. It's a strange, watered down form of identured servitude.
The fact that H1B's have no mobility also depresses wages and reduces the incentive for corporations to be a great place to work because the switching cost for these workers is much higher. So hiring a lot of H1B's actually do offer corporations an incentive that is more insidious than you might think.
That's the bad form of H1B. Corporations bringing worker drones for cheap. But that's why this specific reform can affect the system for the better.
It is a win-win for America and hundreds of entrepreneurs in other countries where the startup ecosystem doesn't exist and ofcourse many would want to build businesses for developed economies than attempt to run something in their home economy which probably can't pay enough. They might go back and build something few yrs down the line or invest in their home countries nevertheless America would have benefited in the mean time.
And this is not even converting all H1-Bs at least the capable ones to start their own firms.