You're making a couple of assumptions:
1) The value of employees can be measured individually. Say you've got 100 assembly line workers. What's the value of losing an assembly line worker? Almost nothing. What's the value of losing all the assembly line workers, divided by 100? Pretty big number! In the U.S. we tend to define "value generated by an employee" in terms of "marginal cost of replacing the worker" but that's arbitrary.
2) That renumeration should be tied to value generated by the individual employee.