* You request website A, which includes 3rd party code from C. C drops a cookie
* You request website B, which includes 3rd party code from C. C knows you previously visited A.
New situation: * You request website A, which includes 3rd party code from C. Website A sends details of your visit via a backchannel to C.
* You request website B, which includes 3rd party code from C. Websites B sends details of your visit via backchannels, and C knows you previously visited A.
Wouldn't you rather such tracking to be out in the open and easily blocked - stop accepting cookies, rather than them creating backchannels to track you instead?
This demo is impressive, but apart from the LocalStorage, this exact same code would have worked just the same 15 years ago.
The web has been a great runtime for a long long time.