Why isn't there a browser setting that passes a standard header to declare what types of cookies you consent to? You set it up _once_ for your browser and you're done.
Anyone who actually worked on browser engines knew it was bullshit that the big internet advertisers (google, Facebook, etc) were using to deflect whichever privacy disaster was in the press at the time.
The rule required DNT not be enabled by default. It was optional for advertisers to follow it, and it was very clear that if there was any significant population that enabled DNT the advertisers would start ignoring it.
And they did. They went even further: they used the DNT state to to track users.
Nothing like this on the client side has any value unless it is made illegal to ignore such flags, and that is actually enforced.
Google's ultimate move however is killing cookies, so they can push their own concept of a supercookie that only they will be able to access.