> <i>Unfortunately, most systems are designed to only allow one path per file.</i><p>Unixes including MacOS have symbolic and hard links. So does Microsoft Windows.<p>Which is not to say that organizing the same set of files into multiple trees is going to be ergonomic.<p>You'd really need a script for that. So that is to say, you have your files in some flat "database" directory, along with meta-data files which give those files multiple names. A program generates the hard or soft linked tree structure accordingly and refreshes it as necessary.<p>Because, for instance, think of the use case of deleting a file. Do you want to hunt for it in five different trees?<p>(I have experience developing sync between a tree and flat database of files from having developed Meta-CVS almost a quarter century ago now.)
Alternately: It's hard to understand a disordered set of tags, so we tend to organize <i>the tags</i> into trees, and then when you shorten the similar-parts they start to resemble paths. :p