I think the point is that if you are documenting the structure of URIs you are focusing on the wrong thing - a RESTful interface documentation should mostly be about the hypermedia (HTML, XML, JSON,...) that the URIs are embedded in - a particular server should really have the freedom to construct the URIs in any way it wants and still have clients that understand the API work.
See: http://roy.gbiv.com/untangled/2008/rest-apis-must-be-hyperte...