I think this doesn't solve the real problem: every person will categorize a document differently and look in a different place. That's the hard part. Creating categories and uniquely identifying them is easy.
For example we have categories like "customer input", "contractual", "work documents" and "delivery". Some technical specifications could go in every place at once. It is an input from the customer, and it has contractual elements, but sometime, we have to update it, and make it part of the final delivery. These often end up all over the place.
You are correct in any case that this is a hard problem and I would love to get some perspective from the author on implementing such a system org-wide.