There's not much preventing you from starting a company and not hiring immigrants.
This is something I'd encourage everyone with strong opinions about work visas to try and accomplish.
You don't change a system by crying about it on anonymous internet forums, you do it by competing against it and making it redundant.
That's missing the point.
Ultimately, companies who use H1B visas will outcompete companies who don't because the H1B system gives them cheaper labor costs. The solution has to come at the regulatory level.
150 years ago, if you told someone "oh if you want safer factories just build one yourself," that business would never survive because they'd get outcompeted by the less scrupulous factory owners who were happy to mangle their employees and just replace them with more desperate workers.
It's better to stop a bad program at the source and improve the lives all of American software engineers.