Way late to this, but to me this ultimately comes down to:

"How do we handle the negative externalities that access to the worlds information at our fingertips has caused?"

In theory parents are responsible for general outcomes of their children.

However, do you expect non-tech, and realistically, non security/networking people to have the toolset to understand how to set up their networks and their devices to block access to this content? It's already a hard problem to solve in enterprise, or at least non Gov/Defense enterprises (hello Bluecoat?).

A company has no incentive to block users from their content like this unless their is a negative effect from letting someone view it who shouldn't. They say "you're the parent block it". It's almost as if a child walked into a bar and said "give me a beer" and the bartender did. Then didn't get in trouble because "the parent should have stopped it".