> I can't think of a really good legit reason for wanting a cross-app unique ID.
The use case that's affected the most by this change is that of advertisers who want to track the performance of ads they buy from publishers, which I think is a legitimate need. The fact that the IDFA uniquely identifies an iOS device (unless the user resets it) is a side effect of Apple's implementation of it; all app advertisers really want is the same kind of first-party conversion tracking for their apps that's standard everywhere else on the web.
Agreed - app advertisers are playing a performance marketing game with their install ads. This change is going to make user acquisition more tedious in several ways:
- some networks will become straight CPC, which will be a pain in the ass to arbitrage to a CPI - there will be a lot of campaign monitoring required
- other methods of install attribution simply aren't as reliable. This will affect the eCPMs of in-app advertising that consisted of app-install demand.
