did you read the entire essay? the author don't say that censorship isn't useful in some cases, he says that censoring is wrong because you it is based mostly on what someone thinks about something rather than how much bad/good would that material/information would do in the society...

here's an example: you can find large collections of satanic and occult books on trackers, but even if most of the people would say that this kind of books should be censored away from our society, you'll notice that lots of people will leave comments saying that those books are a good read, that some of them even helps you understand in a more mature way god and jesus, that those books helped them complete their spiritual life even if they are christians, some will even say that you can learn how to concentrate very efficiently from satanic books etc.

so, should those books be censored?