Re: Lazy/greedy publishers are the reason ad-blockers exist
Not being anything more than freelance, I can't comment on how exactly any particular site organises it, but even in print, ads were never checked for quality by editors, and that was in the good old days of the 90s when we had decent sized editorial teams, and only had to produce one thumping great magazine a month.
Publishing now typically has much smaller teams of people, producing far more content because it's not enough to have a batch of material once a month. There must be things going live all day, every day to ensure the traffic never stops.
(Whether or not that's a good thing is, at least in part, a separate discussion).
But the downsizing of editorial teams means that the idea that a site could produce the amount of content people want, and vet every advert, without needing even more staff, is quite fanciful in my view - certainly if you want to pay the people who write enough to actually live on.
Many sites do have their own ad team, as well as using ad networks - they're the people who will do things like the 'site takeovers' for big clients from time to time. But to get all that low hanging fruit, it almost certainly is more efficient, given staffing levels, to contract this out.
Where the problem lies, really, is in the ad networks and the way in which, thanks to brokers, once you put a box on your site from a particular network, you have no real say in what might appear there, save for some category tweaks and the ability to block something after the fact, if it causes you a lot of aggro.
Ideally, instead of these largely automated networks of ads, we'd have real people curating them, but that would probably require cooperation between various publishers to create their own 'trust ad' network with much stricter rules for what could be accepted.
It might well be possible for a large publishing group - the Condé Nasts of this world - to do something like that, and only accept ads via their own in-house network. But I suspect the economics would be strongly against it for a smaller company with only a couple of online titles.
(Caveat: as I say, I'm a freelance these days, and not privy to any information about the financials; I simply know that on the editorial side it's a case of fewer people producing a lot more work than in the past)