A measurement that measures a metric that correlates can be fine for some purposes. If you however optimize towards it you might run in Goodharts law problems.
Though if something nice has twenty correlates, and you track all 20 of those correlates, you are probably better off than tracking one very strong correlate. (Improving IQ test scores without improving everything else that correlates with IQ would be problematic, for example.)
Though if something nice has twenty correlates, and you track all 20 of those correlates, you are probably better off than tracking one very strong correlate. (Improving IQ test scores without improving everything else that correlates with IQ would be problematic, for example.)