Android has direct filesystem access, but I can't think of the last time I ever used it. The "sharing" mechanism provides a much nicer experience than forcing the user to fumble around in a tree abstraction that hasn't changed in ~40 years. I eagerly await the day when filenames become completely opaque identifiers, never exposed in the UI.
iOS's problem is that there is no standardized way for third-party apps to allow other apps access to a particular document. That's what the OP is actually asking for. Just because desktops have historically implemented this feature as an N-ary tree of (string, blob) pairs doesn't matter.
iOS's problem is that there is no standardized way for third-party apps to allow other apps access to a particular document. That's what the OP is actually asking for. Just because desktops have historically implemented this feature as an N-ary tree of (string, blob) pairs doesn't matter.