" A label which captures this concept is 'Goodhart's Law' -- after economist Charles Goodhart, who posited in essence that 'when a measure becomes a target, it becomes useless.'"
I've seen a similar effect in places where I've worked. A poorly defined metric that is used to rate employee performance will suddenly become the primary focus of the job, instead of actually doing the job.
I've seen a similar effect in places where I've worked as well, that is, public schools. Since the nineties, both school and pupil evaluations have been based on achieving questionable targets using questionable metrics. It's nice to know that even if the metrics weren't questionable, using a target like that would make them so. And not only that, a term, Goodhart's Law, exists to describe the phenomenon. I'll place it up there on the shelf right next to Godwin. Thanks!