Is Duo smart enough to remember when it finds a library requirement with a specific tag? So that it is not necessary to indicate the tag on the other places where this same library is required.
A one could indeed export its requires. However, my idea was was to stay close to the require caching system existing in Node.
As a personal taste, I by far prefer to configure my application in a JavaScript file rather than a JSON file. And I consider dependencies as a part of the configuration process. It agrees with the Duo philosophy which aims to simplify the building process from A to Z.
Although there's no real benefit of doing that over using the manifest other than it's kinda cool :)