Apple hasn't done this entirely out of the goodness of their own hearts. After all, this isn't going to filter ads in native apps, is it? If you're a site that relies on ad revenue you've just been given another reason to live in app-land, not web-land.
Imagine you're a publisher. With one OS release Apple has provided the ability to block ads on the web and Apple News, a charming new platform for you to publish your articles, complete with iAd integration. Which one are you going to prioritise?
Not that this is an either-or thing: just like Google vacuums up your personal data and gives you Google Now in return, Apple will push publishers towards iOS apps while also giving you a great web experience.