There are very clearly many queries with no advertising revenue, because there are many queries that show no ads. Trying some searches off the top of my head that I expected wouldn't have ads, I don't get any ads on [cabbage], [who is the president], [3+5], or [why is the sky blue]. On the other hand, if I search for a highly commercial query like [mesothelioma] the first four results are ads.
> A decade ago I use to be able to find truly exotic articles, I could find every obscure blog posting on every blog with 3 readers
My model of what happened is that SEO got a lot better. When Google first came out it was amazing because Page Rank was able to identify implicit ranking information in pages. Once it's valuable to have lots of backlinks, though, this gets heavily gamed. Staying ahead of efforts to game the algorithm is really hard, and I think a lot of times people's experience of a better search engine comes from a time when SEO was much less sophisticated.
> The most convincing in this is typing first name + last name queries in imagines and getting celebrities who only have the first or the last name.
This hasn't been my experience, so I tried an image search for [tom cruise], curious if I would get other Toms. The first 45 responses were all of the celebrity, and image 46 was of Glen Powell in https://helenair.com/people/tom-cruise-helps-glen-powell-lea... which is a different kind of mistake. Do you remember what query you were seeing this on?