All arguments invoking privacy and security coming from Apple when faced with loss of control over the iDevice software aftermarket should be discarded as nothing more than bad faith excuses.
Why am I being so absolutist? Well, because we know this to be the case thanks to the Epic injunction compliance brouhaha. Employee slack chats show quite clearly that the "scare screens" were deliberately worded in a way that would deter any users from pursuing the linkout payment option, while we now know that it was all a ruse to prevent that option from ever being competitive with Apple's 30% IAP, only for economic (monopolistic) reasons.
We now have court-affirmed precedent of Apple intentionally using privacy and security as a veneer for darker, anticompetitive motives. After that, there's not much more to honestly debate.