Wow how many have you had tonite? The whole point is this season and now (not 6 years ago, or 60), and statistically speaking the AFC has played better than the NFC in the interconference games. On top of that Dibs made a great point that the AFC will be .500 AFC games, and NFC will be .500 in NFC games (wow that feels like such an obvious statement). Since the AFC won more games against the NFC in the interconference games, the AFC is statistically the stronger conference. Your argument about the NFC having tougher games is invalid if the AFC proved to be the better conference, as the more accomplished, better teams more likely come from the AFC than the NFC.
Edit: to clarify Dibs post 96 games for AFC vs AFC in one season would be 8 home teams times 12 games= 96 games. not six seasons, just one