What lies behind the boom in mobile adblocking?

Apple enabled mobile adblockers in the newest version of Safari, and they're taking the world by storm

Wednesday's launch of iOS 9 introduced fully-native mobile adblocking to millions of users for the first time, and they voted with their feet. One specific ad-blocker, Peace, a $2.99/2.29 app developed by Instapaper creator Marco Arment, is the number one paid app in the UK, US, Australia and Canada, while two others, Crystal and Purify, are in the top-ten in a number of countries.

But there's a lot of confusion over what the blockers can and can't do, how to enable them, and what Apple's role is in the whole thing.