Not so sure I agree with this statement either. I'm sure there are cases where the exact same gameday rosters of 3 teams played each other at various points in the season, leading to a situation where
A beat B,
B beat C, and
C beat A.
Who's the better team in that example? Or when two divisional teams split their divisional games. Or in 1990, when the Bills beat the Giants in the regular season, but the Giants beat the Bills in the Super Bowl.