> The deprecation of the blocking ability of the webRequest API is to gain back this control, and to further now instrument and report how web pages are filtered since now the exact filters which are applied to web page is information which will be collectable by Google Chrome.

Which means in the medium run they are looking to deal with ad-blockers altogether because if you can instrument what rules are applies to pages by the most popular blockers you know exactly how to get around those rules. Basically this is a way to dump all that data into Google's pockets so it can slowly but surely get around all of that.