I can't imagine what Reddit would look like with fact checking. Redditors would not be happy if a popular story drops off the front page because someone deemed in inaccurate. How would the incentive structure work?
Some of the serious communities (like AskHistorians) have very active and by-the-books moderators who foster really solid content. A reddit/sub-reddit structure with strong editors and encouragement could be useful in the news space.
Reddit was built with a different purpose in mind. People just use it because its the closest thing you have to what should exist