I think those ideas don't take off because tags don't really solve the problem adequately for normal people.
A folder structure is a self-contained map that will help guide me to the correct document. Each step has hints about where I can go next (sub-directory names), starting from most broad going to most specific. It takes advantage of both locality (similar topics are usually next to each other) and logical, hierarchical grouping.
A tag is a random thought or property stuck onto a file that I now have to remember every time I want to find that file again. I have no way to specify that tags may have a useful hierarchy of other similar but distinct items without manually coming up with a tagging system to give me that. Folders do it by default.
Basically - Folders are a good enough default. Tags might be better in some cases, but you have to be excruciatingly disciplined about using it and I find most people just end up recreating a structure that looks suspiciously like folders.
A folder structure is a self-contained map that will help guide me to the correct document. Each step has hints about where I can go next (sub-directory names), starting from most broad going to most specific. It takes advantage of both locality (similar topics are usually next to each other) and logical, hierarchical grouping.
A tag is a random thought or property stuck onto a file that I now have to remember every time I want to find that file again. I have no way to specify that tags may have a useful hierarchy of other similar but distinct items without manually coming up with a tagging system to give me that. Folders do it by default.
Basically - Folders are a good enough default. Tags might be better in some cases, but you have to be excruciatingly disciplined about using it and I find most people just end up recreating a structure that looks suspiciously like folders.