Any metric must be a proxy.

That's because it has to be a model of reality, not reality, to be operationalized.

Otherwise there's no compression, no leverage.

A map that is 1:1 with the territory is not useful.

But the fact that a map is not 1:1 with the territory means there's a difference between what you're measuring and what you care about.

Swarms that are optimizing for the metric will exploit that difference.