In practice, the behaviour of that loop is predictable and consistent, so people get used to it and calibrate their expectation of the phone’s performance on it

In practice, the behaviour of that loop is predictable and consistent, so people get used to it and calibrate their expectation of the phone’s performance on it. The problem is that a couple years down the line when the battery degrades, that feedback loop adjusts and as a result that performance significantly deviates from what it was originally with no obvious way for the user to understand why or tell whether it even actually happened or if they’re just misremembering what the original performance was. The user can be in the loop in a read-only way. If the control system suddenly makes dramatic & unexpected changes (to accommodate degraded power or thermal performance) the user should be notified so they can rectify the solution (replace the battery in this case). Apple would rather gaslight them into believing their phone is working fine and was just always this slow and it might be time for an upgrade.