When I activate a brand new iPhone I don't get presented with Cnet/Zdnet articles from 7 years that tell me that the OS tracking I'm consenting to now will be pooled with any tracking collected from any Apple app now or in the future.

Apple does not allow 3rd party apps to cross track. Insta app can't collect tracking from the FB app. And that's great. But Apple's apps are excluded from this and allow cross tracking. Apple pools together all the tracking it has access to between OS and apps. OP says they're fine with it because they already trusted the OS. But the OS and the apps are different things. What the OS does is at technical level, the apps know what medication I take, how well I slept last night, or which stores I buy my things in. Combining that is way more intimate than "OS tracking".

I trust Apple more than most other big tech companies but such policies still don't sit right with me. They advertise "privacy" but then eschew their own rules.

Downloading my takeout data after the fact won't prevent Apple apps from pooling tracking data in the first place.