In the supernatural world, the Cowboys will never see a conference championship game until Jimmy Johnson gets on the ring of honor.
In the world we think we know, it's because Dallas hasn't had that many good teams since 1996. Getting to a conference championship game isn't accidental. Teams are either very good, or good and very well coached. The 49ers come to mind.
Besides 2007, 2014 and 2016, what other year did we have a realistic chance? You could argue last year we had a shot if a certain someone didn't make a business decision, and if Dak played like the QB he isn't.