What about manageability, i.e. can a user fit a mental model of the system in their head, or is it too complex to do that? What about the related concepts of consistency and predictability? What about comprehensibility of the metaphors used? The clarity of language? What about ergonomics? Directness of manipulation? What about delight (think pull to refresh)?
Elevating discoverability above all other concerns means that there can be no hierarchy of information. Every feature becomes primary. Everything is on page one, everything is above the fold.
I've had an iPhone for a few months now and I still have no idea what this is about.