Thanks for pointing out BeFS. I only learned about it in the past few months, whereas I was thinking about alternatives to hierarchies for a decade. These related links were quite helpful to my initial understanding of BeFS's unique features:
I am a fan of their dynamic queries. Being able to search all over the file system for certain attributes, instead of merely browsing a pre-canned hierarchy, is a powerful feature. I'm not a fan of their extended attributes though; it seems brittle currently because we have reduced files down to the lowest common denominator of being a finite sequence of bytes, with very little metadata on the side (if you're lucky, you might get a file name and MIME type attached).
* https://systemswe.love/archive/minneapolis-2017/ivan-richwal...
* https://arstechnica.com/information-technology/2010/06/the-b...
I am a fan of their dynamic queries. Being able to search all over the file system for certain attributes, instead of merely browsing a pre-canned hierarchy, is a powerful feature. I'm not a fan of their extended attributes though; it seems brittle currently because we have reduced files down to the lowest common denominator of being a finite sequence of bytes, with very little metadata on the side (if you're lucky, you might get a file name and MIME type attached).