Big companies (that pay real money in RSUs) have bureaucracies designed to thwart this. A referral through the hiring manager practically guarantees an interview loop, but there's going to be an interview loop, with at least one veto point outside the hiring manager's sphere of influence.

Several former coworkers have offered me jobs at their startups, but it's like 2/3rds of my current base and 20% of total liquid comp.