That's a core part of the problem: a path name is NOT just a unique identifier for a file. Desktop operating systems and their classical utilities conflate the

That's a core part of the problem: a path name is NOT just a unique identifier for a file. Desktop operating systems and their classical utilities conflate the "unique identifier" and whatever "displayed title" of a file though which the end user interacts with the file. Users care about "titles" or "summaries" of files, not "filesystem identifiers"; as long as the two are conflated, non-technical users will use the identifier to write titles and thus make the file easy to locate in an interactive GUI. Meta tags are not even in the cognitive horizon of most people.