Apple's strategy is simple. They want to retain control over their customers; at the same time, force the developers into relying entirely on Apple as a middle man so that they can't cut Apple out of any transactions. This way, Apple gets their cut and user's get some level of privacy. That they can get away with this arm-twisting as "privacy" is to give credit to their brand positioning.
Arm-twisting? You are conflating two issues here. Every company wants to retain users and their business. That is how every company operates. You should judge a company on what they offer as an incentive to keep them. Privacy as a service on their platform is a great thing. Compare that to what other companies offer as incentives.
Each time you use the sign in with Apple button, it becomes ever so harder to switch away from Apple products.
Each time your friends add you to an iMessage group chat (instead of, say, a WhatsApp one) it becomes ever so harder to switch away from Apple products.
Each time you buy an Apple home speaker or Apple TV or whatever else it becomes harder to switch away from Apple products.
Google's stuff works better if you're all in but works fine piecemeal. Apple's stuff works fine all in but doesn't work at all piecemeal.
Tech folks should be up in arms about all this, but all you see on this wretched forum are rationalizations involving "business models" and "paying customers".
You want to see a software maker actually care about people's privacy? See Mozilla. Oh but you can't set Firefox as your default browser on your $1200 iPhone, sorry.