[ryanjkirk]

Folders work perfectly in a pure hierarchical taxonomy. Many classifications defy this rigid of a structure, however. For example:

Widget 1: it is A and B but not C, so tag it with A and B.

Widget 2: it is A and B and C, so tag it A, B, and C.

Widget 3: it is B only, so tag it B.

That is pretty simple, but you couldn't represent that in a folder system without permutation folders, meaning you now have folder sprawl, making things harder to find.

This is how servers and ec2s are for almost everyone. Billing codes, environments, teams, business units, etc. A folder taxonomy to replace ec2 tags would be a nightmare.

[ciphol]

Folders have the weakness which you describe. But that weakness is also a strength - folders are a form of encapsulation which, for example, discourages or prevents processes in one folder from destroying data in another folder (accidentally or maliciously). With just tags, that is a bigger danger.