WCAG 2.x was neither peer reviewed nor empirically tested—true. However this is not the case for the candidate for WCAG 3, which is APCA. APCA has been in public beta testing for two and a half years, is the subject of ongoing empirical studies, and does already have journal published peer review, as well as independent peer reviews by PhDs, vision scientists, data scientists, and other technologists.

See a partial listing of reviews: https://git.apcacontrast.com/documentation/independent-revie...