>After the Twitter saga, two of my acquaintances had to leave the US after being sacked. The H1B is tied to your job, and switching employers is incredibly stressful since you need to find someone willing to sponsor you.

Easiest way to fix this issue. Tie the Visa to a state or federal government. They check in and can stay as long as they are working in X industry in potentially Y state. Still not as easy to move, but the company has much less leverage to keep an H1B hostage.