Silly analogy. Playing in the street is not illegal just to protect foolish people from their own stupidity, it's illegal because playing in the street causes accidents and therefore damages other parties.
Let's assume that I am a porn addict and while I'm playing on the "Information Super Highway" I innocently view, with satisfaction, a voluptuous 17 year old daughter/sister of somebody who cares, in provocative poses, having lied about her age or whose pimp lied about her age. Is that an accident? Am I a party to child pornography? Is ignorance an excuse?