Some viewers don't care about being truthful or fair, they tune in to be entertained. Others choose to be lied to from a different political bent. This is fine.
The FCC guy going on Twitter was an own goal, he does have an obligation to objectivity, class and professionalism. This made the story about government overreach rather than stupid comments that some found offensive.
That the FCC took no action was unimportant to many. The appearance of bullying ABC over political speech became the problem.
ABC and the networks for the other failing late night shows are in a bind. Ratings will continue to fall as people have way more options at their fingertips. But now, if they end these shows people will cry about freedom of speech, when it is a simple job performance issue.