Because our non-trivial sample app will be using multiple files now.  We have a sqlite file and a leveldb "file" (really a folder). We will probably want to cache images at some point (and maybe put them on the file system).  I know that this doesn't matter on the iPhone, but think about a desktop app, you don't want all the mx3 files spread around the user's `~/Documents/` folder.

And thanks for the link.  I just need to RTFM and stop being lazy.