[WorldMaker]

Most likely answer: lack of diversity in revenue models.

Outside of ad revenue, search has always been seen as something of a "charity" effort for the internet. It's "boring" infrastructure work that can be critically useful but doesn't really make money directly on its own. No one wants to pay a "search toll" and there's no government agency in the world that the internet would trust as a neutral index to run it as actual tax-basis infrastructure.

[cameronbrown]

Which begs the question, if adblock makes advertising based models go the way of the dodo, what happens to search?