I can imagine many situations where a journalist would hold back on things (names of underage accused, names of spies, locations of military operations, etc.) in order to a) stay out of prison and b) keep the communication pipelines open with their sources.

"Publish and be damned" will quickly lead to you having no-one willing to speak to you.

(Imagine someone who immediately told everyone any secrets they learnt. How long would people tolerate that?)