But the claim that folders can or should be eliminated is seriously misguided.
* Tags aren't enough once your file number exceeds a certain amount.
* File path provides a unique human-readable and human-understand identifier for everyone's file. A system where pieces of data don't have unique identifier is going to be serious drag at some point. Even average people need logical consistency occasionally.
* While folders may be a somewhat hard metaphor for new and casual users to understand, so are tags. A many-to-many relationship isn't actually something people quickly understand fully even if they can quickly get fuzzy understanding it.
* When you throw out the spatial metaphor of folders and files, you've thrown out the guarantee that a file is "somewhere". I've lost and seen other lose files in a disturbing fashion on MACs. Without a keyword for file X, that you just uploaded, you can't "look around" for it.