Hey Mt Union won every game for like a decade and had to settle for crappy Div III championships. The whole conundrum is resolved if you just recognize that G5 schools are functionally in a different league from P5 schools. No undefeated P5 school has been left out and I doubt they ever will.
I look at this from a historical perspective. Once upon a time it was pretty common for multiple teams to finish the season undefeated. Now we’ve got folks complaining some two loss team deserves a shot. We’ve come a long way. And while sometimes the imperfections of the system are frustrating, this season justifies no changes.
as several broadcasters have pointed out, it is rare for the semi finals to be competitive. That just demonstrates the separation at the top any given year is real.