33 yes-no questions which each split the audience in half, uniquely identifies slightly more than the world population.

But any given website is much tighter than that: a regular visitor to Cambridge Evening News is unlikely to be based in राजनांदगांव, and vice versa.

Someone is regularly accessing the website of one local take-away restaurant in Larnaca, a gay men-only dating website, and Ars Technica? That’s probably already got you down to 2-15 people out of the ~3e9 on the internet, with just three specific websites in their history.

Why do you doubt this? Even if you can't always trust the 'unique' part, it is still information which can be combined to produce a more accurate profile.