I think there's actually a great opportunity for someone to create an ad server that only serves first-party ads with no tracking.
I'm talking about something even simpler than that. I have my own website and I have my own advertisers who want to put ads on it. I need a way to serve them and do contextual targeting (e.g. stories about a certain topic) and frequency capping and forecasting and the other sort of basic stuff I expect from Google Ad Manager.
However I don't want any content which could be distracting or plain unsafe for mental wellbeing. One example are the ads for violent games on BlueStacks when I was using the emulator for Android education software for my children.
No thank you. Any content I can't control will be kicked.
Either by using adblockers or by just not using the service.
I dated a woman who experienced trauma in the past and she would routinely get horror movie trailers in YouTube. Even I found them disturbing. Neither of us had any interest in getting intrusive thoughts from watching assault and body horror. Putting in uBlock Origin did wonders for her well being.
The problems are the tracking and the ad networks that kinda treat both the viewer and their site-hosts as consumable resources, but that sites can't realistically avoid if they want/need ad support, because that's where all the money is. Break the ad networks, break tracking (and I mean legally, in both cases—tech means for blocking are doomed, IMO) and ad money won't go away, it'll be redirected to less-awful ways of delivering ads.