The authority of easy
Tim Bray leads his readers through an exercise that shows why Wikipedia gets page rank. In short, it's because FAQ type information is typically readily accessible. It's not the authoritative source, but it is easy, and authoritative sources tend to be the furthest thing from easy.
This isn't that different from using Google to find help on a product because the manufacturer's site is useless.
So, if you'd like to retain your authority on the web, make it easy for people to find the information they care about.