You can definitely put ads without deep profiling. They can even be relevant. Just advertise for fishing accessories in fishing articles. Or hardware load balancers on Slashdot. Why not? Better than serving me whatever someone in my family has looked before (that is if I didn't have an adblocker for the past 10 tears)
Probably most content people read does not easily translate to a product as in your fishing example. Generally, ads with no targeting are not very profitable.
My point was there can be
targeting on content. Magazines have ads. Are they as profitable as privacy invading content ? Maybe not but they're tolerable.
There are ads on HN (the "xyz is hiring", and I suspect a non-zero number of articles posted/promoted to the front page are paid ads made to look like content.
You can gauge user interest by, for example, counting page views. You don't need to fingerprint users, create a catalog of all articles they view, try to guess their interest in certain topics using "AI", and do all the other absurdity that they think they "need" to do now.
