In the modern world information spreads quickly.

If a journalist wants to provide value in a world where publishing is practically free, he has to uncover information that certain people don't want to spread.  This means he has to protect his sources.  And the more he protects his sources, the less credibility his story has.

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I think you could put all kinds of ConfidantSource''''''s in this list... Like Police informants (grass) etc. Where if the source is revealed then the source will no longer provide information. But without the testimony/corroboration, all the information is good for is just so you know.