Why don't browsers just generate a UUID on first run per user.. then anyone tracking can do so server-side.. with a browser/user option to re-generate a new one. It would effectively be the same.. then have a white/blacklist for sending this id.

Or they could make a system where a site can set their own unique id, that they can use.. oh, maybe have a custom key for this value.. and maybe they could call it a token system.. ooh or maybe cookies.

/sarcasm