I know it is a tought concept for many people but that does not make it invalid. Think back to your parents. How did they install values in you?
You are mixing apples and oranges unless you think the solution to preventing children from seeing porn can be given to them as values. I don't think it has anything to do with values. I think it has to do with walking across the room in a public library and seeing a computer screen in front of you filled with a pornographic image. You seem to agree that it's not good for children not to see hardcore pornography. How do values prevent children from seeing something right in front of their noses via values? Its like sitting in your living room watching hard core pornography and expecting your children to avert their eyes and cover their ears. Do you think that's realistic?