Privacy

Not when the conversation tracking is done 100% locally. The only thing sent from the browser is telling a server to increment a counter - a single bit of data. It's hardly any different than a visitor counter that "tracks" how many visitors a site got, which I think would really be a stretch if you claimed that visitor counters were tracking individual users.

I'm not sure if you actually read the details, but this system enables sites to tell your browser which ad IDs are related to an action you're doing (for example on a check out page the site will give your browser a list of ad IDs for the shop) so that conversion tracking can be done locally in your browser. Then, without needing to share any personal information, your browser can tell an aggregator which (if any) of the ads you have previously seen, and that counter gets incremented.

It's literally just a view counter for ads that only increments when the ad is successful, and because the correlation between the ad view and the checkout is done locally, the advertiser doesn't need to link your ad view with your checkout action - your browser did that correlation privately and locally.

Sure no user needs this, but advertisers do everything in their power to track ad conversions and this gives them a mechanism to do that without giving them any information besides "this ad achieved it's goal 30 times", which is so much better than adtech tracking every page we visit so that they can have the information to deduce that for themselves.