I agree with the mobile browser (the only recent change they made, afaics, was to artificially disable most of the extensions and to make tab switching worse), however it is not just about ad networks that people are paranoid about. Tracking is pervasive and there are many players which know way too much about what users are doing on the net.
I don't even care if they track me - what I care about is that they track mostly everybody. Such power should not be underestimated.