This issue reminds me of the IQ testing and measurement problem of regression bias, which likewise arises from statistical artifacts from decades past (when tests were administered to much more narrow and self-selecting groups of subjects than today).

The means calculated using much less diverse series of historical cohorts are still being fed back in to present IQ calculations, which thus retain a persistent corresponding "echo" of the biases in favor of those early test results.

The echo is gradually fading, but some say a clean reboot of the baselines is the right way to resolve historical sample biases which still skew IQ testing away from an accurate modeling of the diversity in present test populations.