Salzenberg's Law of Pretense: Trying to simplify technology by pretending a thing is something else always fails, because the pretense is itself a complication. Putting a mask on a thing does not remove the thing, it adds the mask. It thus requires new technologies to create the mask, identify it, remove it, and see behind it.
Examples: Unix symlinks, Unix device files, Unix pipes -- basically everything in Unix that uses an fd but isn't a local file; DNS CNAME records; and, most recently, making the Perl regex /ss/ match "ß".
Utility Corollary: If simplicity is not your primary goal, then adding a mask may work great.
Examples: same list. Except for that /ss/ thing.