Earlier quoted context omitted.
I think most people would agree a tag filesystem or a similar concept is a great idea. I have wanted one myself for a long time. Yet, for some reason, it doesn't take off. Do you think it is just a problem of implementation?
A few things I can see off the top of my head that would need to be solved for tag filesystems to be able to take off: 1. Inertia. Most software assumes hierarchical filesystems, and assumes it can control some portion of that hierarchy. This includes things ranging from search paths for various things ($PATH for binaries, library paths, etc), temporary files, preferences files for applications, assumptions made abou…
Mainly, the more complex tags which can themselves refer to other tags.
1. This is probably the trickiest one. You may be able to do some sort of translation between a hierarchical system and the tag system using tags themselves. You could have a series of tags that refer to each other, such that the hierarchical location is essentially encoded in the tags themselves.
2. Again, maybe just special tags?
3. Yeah, again, tags. Just tag the thing with the media it's on.
4. Aside from the basic UI side of things which should help, there is the idea of shared tagging systems. I don't recall if that came from the author or another commenter on HN. And you can basically ask the same question about hierarchical systems. It's not exactly a solved problem there either.
5. Again, the complex tags. Just make a tag for the project.
6. Obviously UI is a big question. I'm not sure how it relates so much to media-specific browsers though. They basically present a different view of a section of a filesystem. You have to do some work to let them do this, or else use a system like iTunes and buy all of your media through them.
7. Although I feel this is well addressed by the author, one thing I think you aren't considering is that each of these applications requires their own setup in order to provide that view. You often can't just take the directory from one of these programs and use a different program to view it and have it all work properly. If you only have one program for each media type and never want to use anything else that works, sort of. Many years ago I directed iTunes to redo the file layout for my music collection and rendered it effectively useless for direct browsing. I never really recovered from that due to the time involved to sort it out.
And mutability isn't totally handwaved away, again with the complex tag system you could tag mutated works with a reference back to the original. This doesn't cover the case where you don't wish to retain the original, but then you could just do a simple find/replace with the old and new hashes in the simplest case.