In the print age, the state to some extent could keep material from children without interfering with adults. The Internet now makes that impossible. Since there are no physical boundaries in cyberspace, anyone can go anywhere anytime. Copying and forwarding information is nearly costless. There really is no way to fully suppress any material.
All government can do is raise the costs of finding it.
There are several lessons to be drawn here. First, the suppressors of vice will seize on any new technology to reinvigorate their crusade. If you respond that older technologies did not lead to widespread corruption of children, they'll respond that the new technology is entirely different and that we need new rules. Second, because Americans instinctively object to being told what they can read or look at, the vice squads will seek to disarm them by saying that censorship is necessary to protect their children. Decent people who don't give the matter sufficient thought will thus be hornswoggled.