So there is an onboarding process that is skippable, and it would appear that either most people either do, or at least click-through. While the onboarding doesn’t show every gesture and shortcut, it does show how to “figure out how to use this device”.

And herein lies the problem, and it’s not exclusive to iOS. No matter how much hand holding there is, if the user doesn’t engage, then it’s a lost cause. As the saying goes, you can lead a horse to water, but you can’t make it drink.

Discoverability is as much about trying something that you know works elsewhere as it is showing direct affordances.