> The endgame will be all/most websites embedding 1st party ads and tracking
The problem with first party tracking from the PoV of the advertisers is that the feedback they need goes through the site their ad is on so it is possible to be faked: "Yes Mr Advertiser, we really did send x000 ad impressions to {addresses} this day, honest guv'ner."
And from the site's point of view the adverts now become a little more admin to manage beyond just slapping in a reference to 3rd party JS and adding a <div> for that code to target to insert the advert.
They could address that by going the other way. Instead of serving the ads from the content provider's server, serve the content from the ad provider's server.
Essentially, the ad providers would also become hosting services.
Many content providers won't like handing over as much control as such a situation may imply though.
It also creates single points of failure that did not exist before. If the ad service is down, your content is (potentially) down too rather than just being served without working ads.
The problem with first party tracking from the PoV of the advertisers is that the feedback they need goes through the site their ad is on so it is possible to be faked: "Yes Mr Advertiser, we really did send x000 ad impressions to {addresses} this day, honest guv'ner."
And from the site's point of view the adverts now become a little more admin to manage beyond just slapping in a reference to 3rd party JS and adding a <div> for that code to target to insert the advert.