Comment by robcohen

Ah yes, the sybil attack. This is why establishing an identity is useful, and worthwhile. An identity with no proof is likely not a real person, and therefore has little value in being advertised to.

If you're a real person, then yes, it is valuable to show you things.

Want to know how I'm right? Because fingerprinting browsers and tracking people is how we establish that they are real in the current advertising world. Advertisers pay for that. Thus it has value.