Having developed my own tagging program http://www.taggtool.com I can offer the following thoughts:
It is super useful to be able to cross-reference multiple files using tags but
it involves a lot of upfront and ongoing effort to add tags to your files although automatic rules help.
Technically on Windows it's a challenge to code such a system, where do you save the tag metadata? Ideally in the file but that's only possible with a tiny set of file formats.
Alternative Data Stream offered a possible solution but it feels like a half baked solution.
The other option is to store the metadata in a database which introduces the new challenge of keeping everything in sync.
It's a shame that the native OS doesn't provide a robust metadata storage for files but that's the way it is at the moment.