When I set up macOS recently, telemetry was off by default; it was opt-in. Not sure about iOS, but I presume it is the same. So you are correct that device makers collecting telemetry have a certain advantage, but most app/content tracking systems I have interacted with are opt-out and therefor, in my view, are more invasive.
The app tracking dialog on iOS is technically opt-in, but the way it is written reflects that the system and the user have limited control, the "Ask App Not to Track" button implies that Apple acknowledges that their attempts to block tracking are best effort and are not guaranteed to work, because new and clever ways to implement tracking are being created on a regular basis.
Even when turning telemetry off there's still a huge amount of data going to apple.
For example the gatekeeper revocation check leaks a lot of data about what kind of apps you run. I'm sure some departments of apple really care about privacy but it's a big company and clearly not all of them do.
The app tracking dialog on iOS is technically opt-in, but the way it is written reflects that the system and the user have limited control, the "Ask App Not to Track" button implies that Apple acknowledges that their attempts to block tracking are best effort and are not guaranteed to work, because new and clever ways to implement tracking are being created on a regular basis.