Because it should never be "4" teams. Ever. The fact that people like the current set up and think that with 132 teams we don't need at least a 16 team playoff is why you're statement is insane. If you're 11-1 you should be safely a part of a playoff in all sports. Supply and demand doesn't make sense here.Why? With only four slots (for now), and what? 132 teams? You could easily have two 13-0 teams, two 12-1 teams, and a 12-0 ND. Supply and demand. An 11-1 team is much more likely to get the 4th slot than the first.
The entire point is that playoff expansion (ideally to 24 or 32) is desperately needed unless the SEC/Big Ten form their own league--then 8-12 will work.
Again, if a team is squeaking in with 1 loss then the format is wrong.