[fatratchet]

> But it's there as a nuclear option if needed.

But only for bigger sites I would assume. Everthing going through the servers of the site seems to have a huge potential for ad fraud by smaller sites. I can't imagine any ad networks beeing happy about having to (at least somewhat) trust smaller sites.

Alternatively everything/something going through the ad networks seems like a huge problem (cost, flexibilty etc.) for small sites as well, especially for any bandwith heavy content.