Could blockchain solve the “Master Cookie” legal/privacy advertising issue


I remember years ago when the EU Safe Harbor data privacy agreement was in the news, it was also discussed how the “master cookie” that would enable advertising networks to track users cross device, cross browser, cross platform, would never be possible as it would imply serious privacy trades offs which I cannot fully understand at this point.

Now with blockchain technology as a service in some cloud providers, Identity protocols on blockchain, etc Is it possible to:

– Provide full traceability from an specific user (a public key that cannot be related to any private data such as email address) cross device, cross browser, cross platform? User would only need to authenticate with public / private key on each device, browser, platform.
– Enable users to identify (through the public ledger) who is following them, with whom is their web history data shared and with what purpose and allow users to opt-out.
– Create an ecosystem with incentives that would make it interesting for Users, Advertising Networks, Publishers/clients to allow for full transparency empowering the user to take the decisions on web history sharing and cookie data sharing, while delivering better ROI to Clients/Publishers (the ones spending the Ads dollars) due to better targeting and finally giving Users a better web experience with real native content in the right moment instead of Ad saturation of irrelevant messages due to lack of traceability?

Not sure If I made my self clear enough, but curious to know your point of view and if there is anyone working on this topic in the Blockchain ecosystem.