This aspect of information goods is oft quoted as a distinguishing feature whose existence supports a radically different approach from previous publishing methods.

It's true that the marginal cost is dramatically decreased with digital publishing. But there's a big difference between "closer to zero than before" and actually zero. The marginal cost of digital information goods is not actually zero. That people are willing to trade their privacy in exchange for someone else bearing the costs of managing information is one piece of evidence of this.