I concur, those were the two best teams not only in 1973 but likely for several years of that period. The UGA team in 1980 was lucky as H several times, the 1981 team was better and lost two games. BYU is a good example of a NVG team that "won". I bet Nebraska has some great teams that tripped up once, and Ohio State in 1997 I think it was had the stumble with a great team.
It's tougher, less likely, today, for a "Cincinnati" level team to win the playoff I think.