It's refreshing to hear that if a User can ... then hackers will ... so we don't allow that. So if you want ... then don't buy Apple.
Thread!
It's really as simple as you write. Apple has chosen to make that as impossible as possible. Everyone knows it, everyone can choose it or not choose it. To further that point: non Apple options are more widespread, far more available, FAR more hardware options than iOS.
The worldwide smartphone market is, or in the near future will be, about 1 in 6 iOS and about 5 in 6 Android. The 5 in 6 insist to the 1 in 6 we MUST do it their way for seemingly no reason other than a vocal slice of the 5 in 6 just don't like it. It's laughable on its face. (they will then argue with their appeals to authority all the way to Apple is just trying to make a lot of money. I suspect those and new hits will keep on comin too).