I think getting recommendation of similar books to read is a feature rathen than a bug. If you ask your friend to recommend a book the first question they'll usually ask is 'what kinds of book do you like'. Either that or you get recommended whatever NYTimes says is the bestseller (which may not match your taste).
There you have it. And beyond that, the corporation will sell the data to whoever if profitable. They will abuse them any time there is anything to gain.