The only plausible explanation for Brian Williams — soon to become a verb — is that those notable prior anchors had correspondent experience in war zones etc. Some for many years. Williams wanted to embellish his slim resume. So he did.
So how would it feel to go home over the weekend and learn your version of reality doesn’t exist – and never did? Obama must have had several of those experiences.
Actually, Susan Rice and Hillary had similar experiences. It even happened at the IRS.
Of course their credibility required the willing suspension of disbelief anyway.