Is there a good explanation why didn't gdpr "make websites obey do-not-track" (or a similar set of rules/whitelist/blacklist that can easily be set once in a br

Is there a good explanation why didn't gdpr "make websites obey do-not-track" (or a similar set of rules/whitelist/blacklist that can easily be set once in a browser) instead of prompting for manual consent every time? I never see it when a discussion like this arises