Exactly the same for startup stock. The company granted the stock to investors for cash and employees for their service as part as a compensation package, and as the employee fulfills their service, they earn the equity as well as their salary.
>Are there any other management practices where one would optimize for former employees at the expense of current employees? I can’t think of any.
This is exactly backwards. You don't offer the 10-year clause ex post, you do it when the employee signs. That's optimizing for new employees, not old ones!