Note that this doesn't require an all-new crawl/engine: just for an existing engine to offer an advanced operator that filters ad-drenched pages from results. Even just an operator that eliminated AdSense sites would be a big win for some queries.
While technically feasible, this would rule out a large number of high quality content sites which are currently ad-supported. For example, specialist community forums often carry ads just to cover costs. You need to allow for a different funding model for sites like that, such as subscriptions.
Note that this doesn't require an all-new crawl/engine: just for an existing engine to offer an advanced operator that filters ad-drenched pages from results. Even just an operator that eliminated AdSense sites would be a big win for some queries.