I like what you're saying, and wish companies thought like that, but most lots of companies look at devs like fruit to be squeezed until dry, then discarded. This is particularly true in game dev. Granted, the devs are partly to blame for going along with this terrible plan, allowing themselves to be pushed to work 80 hour weeks, all-nighters, etc. A smart employer would actively prevent their employees from working like that, because you're right when you say that a dev can be worth a great deal more if they stick around a while.