Moderators are not at all like editors. Even the most laissez faire editors must decide what appears in the publication, even if they do not edit for style. Though they may not infringe on a writer's style, editors are expected to catch obvious errors in grammar and spelling. Errors in fact fall first on the necks of the editors before they are pinned on the writers. Moderators work under different mandates. They usually do nothing about errors in grammar and spelling. Errors of fact might be contradicted, but the moderator is usually no more or less a peer than any other poster. Moderators do intervene in discussions in ways that editors usually do not.
The best way to perceive the matter is in the stark contrast between an unmoderated newsgroup such as Rec.Collecting.Coins and a heavily moderated forum such as cointalk.org. In the middle are most lists, Coin People, and many unmoderated groups, such as Rec.Collecting.Paper-Money. RCP-M does have its slice of spam, but the cut is much thinner than on RCC.
Just as editors create the style of a publication that brings or loses readers, so, too do moderators of a group, list, or forum attract or repel participants.