"Apple are making quite a big deal about this. The recorded data is of an incredibly private and personal nature and they’re preventing it from being passed over any kind of network except as part of a secure backup.
[...]
A more real world case is that hospitals are starting to create out patient monitoring apps. Whenever a patient uses their blood pressure monitor, the hospital app gets notified of the new reading, sends that data to the hospital computers, a doctor might then review it, see there’s a problem and call the patient in."
I don't see how both can be true, and I don't know which I would want. On the one hand, the first is highly desirable, but that second use case makes lots of sense, too.
Reading https://developer.apple.com/app-store/review/guidelines/#hea... I think the first isn't entirely true:
"27.5 Apps that share user data acquired via the HealthKit API with third parties without user consent will be rejected"
So, that's not a blanket forbidden. And likely, they aren't preventing anything. That game with an on screen heart rate indicator could easily encrypt heart rate information and send it alongside other data to a game server. It would be hard to detect that.