It seems that what you are describing though would tend over time to result in a search engine that is principally geared towards returning commercial results rather than amateur/hobbyist results since the interests of search/potential advertisers are always going to be in closer alignment then hobbyists who will almost never be running an ad campaign.

This has been my main criticism of Google's direction the last 15 years or so. Seems like search results use to populate handsomely with personal sites and blogs run by hobbyists uninterested in extracting a dollar from the visitor. If the search results could return either (a) a link to a book sold on Amazon or (b) some Phd's site discussing the topic it seems likely that (a) wins and (b) gets buried somewhere on page 2.