The internet and Usenet did OK without moderation until Eternal September and the invention of SPAM, when internet culture started to die. RIP. Before that a new arrival was expected to figure out netiquette, and everyone else would behave accordingly.
Ever since then there has been an fairly steady slide. The arrival of astroturfing corporate and special interest groups, trolls, and platforms that assist the amplification of effect by actively seeking to avoid any moderation has just intensified things. Those places without moderation deviate to lowest common denominator with astounding speed. We've seen it time and time again, and as a result many sites have closed down their discussion areas entirely. See reddit subs with and without active heavy moderation. Moderating does not rule out anonymity, nor should it.
Without moderation commercial interests, political groups and trolls will ultimately ruin all locations that attempt to allow reasonable discussion as it is not in those group's interests to see a virtue in being virtuous.
The few places left where you can have reasonable discussions, including on controversial topics, are those that moderate hard. They don't censor.