If you ever wrote a specification, you've come across the following problem: Once you finally built your spec you need to cut it into feature-tickets, spec units that you can properly follow in your project management system. This basically duplicates your information, in a fluent text and a ticket version. It's a lot of extra work and worst of all it disconnects your specification from your project management system.
In most cases this means that from that point on, the written document is dead: the fluid text version will never be rewritten. A recipe for a communication disaster.
