Good article, but I think the conclusion he makes is way off mark:

The good news is that the things users want to keep secret are almost always the least important things to online advertisers. It turns out that knowing people are trying to buy new washing machines or plane tickets to Hawaii is vastly more monetizeable than their names, who they were dating, or the dumb things they did in college.

Your preferences + your email address is extremely valuable to online advertisers. And an email address is generally a personal identifier. Well, all of mine are, even my gmail one is an identifier if you know what I do or what country I'm from as I have a fairly rare surname.