Even a flickin' unix whiz doesn't care about, say, which disk sector a file is located on. In fact, if they are using a distributed file system, they also can mostly ignore the physical location of the data.

Your spiffy net of tags is a way-to-find data. A officially "file system" is a way to find data. Each has some flexibility, some lack-of-ambiguity and some persistence over time. You may not care about the uniqueness, ambiguity and decay over time of your tag based way-to-find data. But that just means you've got a convenient but half-assed file system. Moreover,