I hope this is the correct site, I lose my way between the 4 sister sites :)
Let me ask the question this way. all file systems I have seen before are hierarchical, that means a root directory, with some branched directories, and so on until we have files residing in these directories. except for AS/400 file structure, where it has a concept of a Library that serve somehow as a directory but one level only.
Why not have directory-less filesystems where files are placed in a single location, but the file identifiers would be referenced by a database of tag/ file relation ships.
This way there will be no need for symbolic links, one file may have multiple relations to multiple subjects, not only a single parent directory to contain.
I hope the idea is clear.