I know that kind of nonsense wouldn't fool you but a lot of voters got all warm and fuzzy believing they might get an invitation to join George Bush "down home on the ranch" for some cold Lone Star and manly conversation.
It's rather amazing how lazy people are when it comes to choosing the next leader of the free world.
As for moderators fact checking, I think they have a responsibility to the viewing public to challenge the more egregious lies if they're serious enough. If Trump lied about spending three years in a mental institution, I'd expect that lie to be corrected on the spot with known facts.
Otherwise, a challenger has an opportunity to rebut the lies themselves and let the public decide.
Ninety minutes isn't enough time to dwell on the minutia of all Trump's lies but yes, a known liar like Trump should not be given free rein in a debate without being challenged by the moderator when he goes overboard.
In fact, I think the public has a right to demand it.