Counterpoint: what if older societies already put in place censorship laws that were so successful, they effectively scrubbed any cultural memory of similar "works"?
Perhaps we should write our rules based on what we want in the future rather than what our ancestors did?
Is goatse.cx still up? I would check but growing up with the internet as it was, I've seen enough Goatse in my lifetime that I really don't need to see it again.