I believe we're at a point where a legitimate proof of concept could emerge where given a first and last name of a person, one could theoretically track a person's location and browsing behaviors for an indefinite amount of time. Granted, it would require that the person not clear their cookies, grant geo-location on their phone and that you have a bit of money to ensure you win enough ad impressions in that time period. The takeaway would show that people aren't as anonymous as they think they are and that with enough money and motivation, someone could gain valuable insight into your behaviors.