In many many many cases it's not the manager choosing to do that. Its our brilliant job creator class demanding that he does

Bad manager: "I have to give you a bad rating because of the company-wide LoC metric."

Good manager (to good engineer): "can you please churn some code to update your LoC metric so I don't have to give you a worse rating?"

I'm sorry but any manager who just claims they're a passive victim of company-wide mandates is a lazy and bad manager.