As a user who hasn't yet developed a lot of trust with most adtech companies in the mobile space today, I'm happy to see this. (By not yet developing trust, I mean across several fronts: their security rigor, their concern for end user privacy, their business practices and ethics broadly, etc. Would be happy for companies in the space to prove themselves out on these fronts, but it hasn't happened broadly yet, imo.)

This will cause some hacks in the industry, though. We might see a resurgence of device fingerprinting within apps, and it might lead to an increase brand-like advertising vs pure performance marketing. Also, users that have ad tracking enabled might be considered more valuable and unless the practice is banned by AAPL (or maybe it already is), I could see apps that rely on ad revenue to a large degree incentivizing users to enable ad tracking.

I wonder if the default setting will be to limit ad tracking or not. I assume not, but this could have a really large impact if it's on by default.