Google does that by storing my data, many kinds of my data. You making the distinction between data that "the user knows and understands" versus data that "is obscure to the user but advertisers care about" is a matter of marketing, in that as the former is easier to charge the user for.
My point is that the argument of "you're not paying for storing data X therefore fuck you" is a silly one, because you're also not paying for storing data Y, and neither are the advertisers.