This may not be surprising at all actually. Look at how they form their feeds. It is hyper-dependent on a singular metric: engagement. Engagement doesn't mean you're making your users more connected or happier, it just means they are using your product more (e.g. fighting and yelling at one another). Goodhart's Law in action. But I agree that something like human performance is incredibly difficult to quantify and requires a lot of nuance. But people, and especially bureaucrats, don't like nuance.