Well the information is not "sold" per se, as much as it's bundled with many other people, decoupled from PII, and is the equivalent of saying "10% of people talked about the football game today."

Further, I believe a service like Google Contributor does what you're implying, but it doesn't get much press - which doesn't surprise me: the overall market deems free content worth that privacy "trade-off."

I don't understand why this is necessarily a "bad" thing -- it's like the equivalent of a real-estate broker telling me that 10/20 houses on a block have 2 bedrooms, and the other 10 have 3 bedrooms, even though I know nothing about the people living in those houses.