That's the big takeaway here. As far as I can tell, Apple really stands to gain nothing by blocking trackers when it's one of the smallest concerns I have with regards to modern digital privacy. Snowden didn't warn people about ads, he warned people about massive surveillance campaigns operating just out of view of the public.
The largest modern privacy concern is being dependent on any one private party. Relinquishing all control of your data, software and hardware to the largest company in the world is a security concern. Whether it's a sacrifice you're willing to make or not is a different story.