Obscenity may be censored - when it might otherwise shock the unsuspecting public. I never have looked at any of the alt.sex hierarchy. Once a public forum exists, it may not be censored, although the participants may agree to self-regulation. I remember once wondering what was really in alt.flame, and the first article convinced me that I had read enough. The alt.flame group is there with a good reason - otherwise people who do not want to read that material might have to read the same articles, but in their news group.
Archives reduce network load.
Netnews reduces network load. I can also personally see no great benefit to every person having a gun or two except that we would all either be much more polite or on the way to an ambulance. I am not an absolutist, and everyone does not act the way I think everyone should. I do not act the way I think I should sometimes either. That is a nice .signature.