You can already do this by scraping their follows list and building a pseudo display of what a person looked at.
It’s a subtle but important (and hard to admit) difference; because it relies on realizing that we’re not special snowflakes, but we have a whole group of people we’re like.
> because it relies on realizing that we’re not special snowflakes, but we have a whole group of people we’re like
yet buckets become more valuable the more specific they are (for example "dad of 3" is more valuable than "male"). it's not hard to see how that would scale into "every detail about the person would allow maximally manipulative advertising = most valuable", just think about any vulnerable position you might find yourself in that can now be used to manipulate you