That's correct but you're not playing along with the analogy. Analogies are not meant to be exactly the same.

The analogy for the jazz festival is that the hungry & thirsty attendees in a "walled-garden" of the park are offered up as so-called "products" to the vendors to be sold food & drink. Hence, "You Are The Product".

If we want to dismantle the analogy in the direction of Facebook, we could complain that "Facebook doesn't sell food & drink to the web surfer so I don't see how the jazz festival applies."

Well, that's how analogies work. You have to look for the commonalities instead of the differences.