In other words a system for non-ambitious dinosaurs to get in their cronies and milk the system while almost being assured of a job for the next decade
That was the first thing that sprang to mind for me too. You don't always get a referral right. I've had wonderful friends who have made lousy coworkers, if I was even more incentivized to protect them I think you'd see a pretty stagnant workforce develop over time.
The point being a referral based system incentivizes people to bring in quantity to stack the odds in their favor. Quality gets sidetracked, not necessarily maliciously.