In the olden days (when NNTP was a more popular protocol), almost anyone could post almost anything to almost any group. There was moderation, but mostly in more focused groups or announcement-centric groups where replies were not expected. To moderate, you, yourself, added people and subjects to your own kill file. This meant that the platform was mostly free of censorship, but the participants could choose to engage or not with trolls or charged topics. If they chose to disengage, they simply wouldn't see it. Like going on /. and setting a filter level of 5 for viewable comments.