historically to this point we are doing better than them yes, and you're statement about pre 1970 is absurd. there was a lot of great football played before the merger by some of the greatest players ever. The biggest reason the steelers can be used as an example though is that the Rooney's have always owned them. They didn't just stumble into SB wins. It took them a very long time to build what they have.
By your logic the Arizona Cardinals are one of the best franchises ever.