The question is whether your ads really need to be targeted to individual persons (requiring a huge surveillance infrastructure) or if you can just sell ads to some sponsors and everybody sees the same ads.
I prefer the second option. Nothing wrong with ads per se.
It's just not feasible for the sites like parent commenter described to look for sponsors, sign contracts, etc. We are talking about, say, $200-600 per month in advertising. You can spend more time searching for next sponsor then you will make from ads.
They can monetize by working with 3rd party, like SSP, who will sell the inventory programmatically. But to monetize effectively, that 3rd party will do tracking, that's true.
I prefer the second option. Nothing wrong with ads per se.