There's plenty of opportunities for members to be helpful without being made moderators or maintaining guides, you just have to keep an eye out for them.
As far as why the guide isn't stickied, this guide as well as the collectible price guide aren't actually official and are based solely on community observation. By sticking them and making them appear "official", it creates something called price fixing and tends to skew the economy here, and we'd prefer it if sellers simply accepted the price they feel is fair or that people paid what they wanted for their favored villagers rather than looking at these guides/tiers as something that's officially endorsed.