[digitalsushi]

Blocking porn requires that you draw a definitive boundary around a subjectively defined area. You'll always draw the wrong shape because everyone has their own.

So now you're blocking stuff that people think you shouldn't, like girls in bare ankles or breast cancer papers or who knows, and now you're requiring people to divulge their thoughts by requesting access to it.

And now you have an insight, however primitive, into someone's thoughts. And you have no right to be in there.