This is why I happily set Brave Ads to show me the maximum amount of ads per hour. Brave is serving ads in a privacy-conscious implantation which uses local machine intelligence to determine interests. There's no broker trying to sell your data to advertisers and yet personalized ads can still be served. Also, Brave Ads show up as a notification. Much more aesthetically pleasing than those whole-page ads that some websites have unfortunately adopted.

I agree that their system avoids a lot of the ethical problems that would come from leaking all the user data to ad networks.

Having said that-- ads are an unethical distracting nuisance. From the evidence of every use case outside of esoteric journals they will increase their aggression even to the point of threatening to destroy the value in the medium to which they are attached. Try listening to a Youtube version of "Tristan und Isolde" that has ads turned on. It becomes a broken video file at that point.

Worse-- web site owners have already shown that they lack the expertise needed to asses the ethics of the ad delivery systems they use. I can't tell you how many otherwise ethical open source devs used to have a fake download button from ad malware right above the real download button for their software. Never mind that the previous incarnation of Sourceforge just decided to turn evil one day and bundle malware. I don't think Github would do the same thing today, but most open source devs have no plan of what to do if they did. So we're not any better off today in terms of awareness of these problems.

Plus, adding cryptocurrency tokens to that same confusion in no way makes it easier for those same devs to suss out the ethics.

Edit: just to be clear-- the fake download button came from the ad network domain. The site owners almost certainly just leveraged ads to pay the bills under the logic, "How bad could it possibly be for the UX?" They'll ask the same question of Brave's system, or any system, and have the same lack of expertise with which to understand the given answer.