Well, they didn't hide the scrollbar on desktop until Lion, at which point Steve was in quite poor health.
On mobile, and particularly on screens the size of the original iPhone, hiding the scrollbar is a necessary tradeoff for screen real-estate. It also doesn't necessarily hurt usability if you know the exact screen size you're designing for, and can ensure elements are never fully cut off on your initial view.
On mobile, and particularly on screens the size of the original iPhone, hiding the scrollbar is a necessary tradeoff for screen real-estate. It also doesn't necessarily hurt usability if you know the exact screen size you're designing for, and can ensure elements are never fully cut off on your initial view.