4.2.3.f says, "to ensure that documents of external origin are identified and their distribution controlled" It's more than identifying their source, it's about making sure that new versions are made available to all who need them. There's little worse than a customer discovering that a revision to a customer-originated drawing or specification has not been communicated to all involved and that the organisation is consequently making non-conforming product.
4.2.3 also says that "A documented procedure shall be established to define the controls needed ..." The word "need" is important. It means the controls that the organisation determines it needs--not what an "idiot auditor" thinks it needs on the basis of a literal, mechanistic reading of the standard. One way to determine "need" is to consider what will happen if distribution of the document of external origin is not controlled. Therein lie the benefits of this requirement. So ...
If we use an out-of-date catalogue, we call a supplier for a product that is no longer available, or costs more than we expect, or doesn't do what we think it does. In many cases, no big deal, supplier will correct us and life moves on. If we're the purchasing department and we make a hundred such calls a day, maybe we ought to control catalogues in order to avoid wasting our time. If an engineer makes design decisions based on an out-of-date catalogue, costly rework might be involved when the error is discovered. If we're a marine regulator, it sounds like it's vital to control catalogues.
If we use an older edition of Juran than is currently available from Borders, how much trouble are we in? Very little, I would imagine, unless our product is critically dependent on material in the latest revisions to the book. Of course, if we work for Mr Juran and we haven't read the latest wisdom from the master ...
If we're doing R&D and the customer has written a technical specification that runs to a hundred pages, revises it, and finds that while fifty of our engineers have the revised version another couple of hundred are working to the old one, the customer will be seriously annoyed, especially if it's a time and materials project and the non-conforming product is being made on the customer's nickel.
If we claim our product conforms to an international technical specification, and that specification changes, and our engineers do not get informed of the change, we could be in breach of contract.
If we use the 1994 edition of ISO 9001 instead of the 2000 version, our colleagues giggle hysterically and ask us which planet we've been on for the last several years.
Hope this helps,
Pat