Except magazines, billboards, and TV ads can't monitor your activity and parse it to tailor their advertising to you in a more effective way. Not doing so would defeat the entire purpose of having the data at their disposal. The whole reason these companies are successful is precisely because they can datamine you, not in spite of it. You'd have as much success getting major corporate retailers like Target and Wal-Mart to drop Big Data based product correlation: i.e., none.
All of which is true, but that still doesn't mean that "you are the product" doesn't also apply to every other form of advertising. When you watch TV, the product is you, the audience, being sold to advertisers. They lure you in with their TV shows, but really they're just trying to serve you up to advertisers. "You are the product" applies to commercial TV just as much as it does to Google or Facebook.
As I said, G and FB represent huge and unprecedented invasions of privacy, but that is irrelevant to whether or not "you are the product".
"You are the product" is mostly a result of the advertising being 1. "smart" and 2. being far more successful than "dumb" advertising as a result of it. If it wasn't more effective, they wouldn't invest in all the overhead necessary to pull it off.
Again, all true, but "you are the product" whenever you watch commercial TV too.
The reason people claim that "you are the product!!!!" is simply because it is a nice little catch-phrase. But it's nonetheless a dishonest one, because you "being the product" isn't actually that big a deal. What
is a big deal is the massive, pervasive invasion of privacy that you were describing earlier; the reams and reams of personally identifiable information that G and FB have on you; and the complete lack of regulatory oversight thereof. Indeed, governments and regulators are complicit in this -- as part of "counter-terrorism" and "anti-piracy" initiatives, governments are themselves not only amassing giant databases on people's browsing habits, but tapping into private companies's databases, too. That's what's
really scary here, not the trite and rather commonplace phenomenon that you are being use as an audience for advertisers to push products onto you...