Reporting the (not so) obvious
I'm sure there are news consumers who don't realize that a damaging story about candidate X was spurred by an email from a flack for candidate Y.
Yes, there are. They are the <1% of the populous who closely follows political journalism (note: stat pulled out of my ass, but probably close to accurate).
Ironically, Cox may be highlighting one of the myopic aspects of beltway journalism: the assumption that what is general knowledge within the beltway is general knowledge outside the beltway.