I read that article too. Dowd said that the big mucky-mucks at NBC had been warning Williams for years against embellishing his resume with stories that were not true. But with many of them not around anymore to monitor or scold him, he just continued. Why he did it, we don't know. I speculate that he is a narcissist and needs to feed his ego so that he looks better to himself than he knows he is. Did he need to do it? Absolutely not. He was already at the pinnacle of his career and didn't need to artificially advance it.
He's a liberal and a liar. What else is new?