Field notes
An initiative is usually surrounded by background material: requirement specs, existing architecture sketches, market research, regulatory documents. If that material is not available in the same place as the solution proposal, every reviewer has to track it down on their own, and the risk arises that different people work against different versions.
The Documents tab is not a document management system. It is a single entry point to the material that this particular initiative rests on, so the solution proposal can be read in its context.
Seeing all the documents and their history behind the making of an initiative can be very informative, and may point to a long and/or winding road towards a solution proposal. :)