By that I mean, if you're a site about say, board wargames, and there's some new board wargame that wants to advertise on your site, ok. Edit your page to add an ad graphic with a link to the seller. That's cool. And maybe the people reading your page will actually want to buy it!
But there's just no way that third-party ads through some generic ad network will ever achieve that fit or reliability. And ads based on tracking people's data and suggesting things based on what you interacted with on social media or whatever? That's always going to be hot garbage at best. Adding in a third-party ad network (and probably behind that brokers and other middlemen) can't possibly make it better, it can only make it worse. So that's what we have today.
But go back to simple static ads relevant to the content of the page and problem solved.