What you completely fail to understand is that the NCAA has different rules for the P4 conferences than they do for the G5 conferences. They, in fact, are NOT playing at the same level. Not only do the schools recognize that, the NCAA does as well.
The fact that you want to pretend that big time college football is the same now as it was 25 years ago doesn't mean that it is, it means that you have your head buried firmly in the sand.
And in any event, the NCAA does not run the college football playoff. What the NCAA may want or may not want has nothing at all to do with what actually happens. If the NCAA somehow tried to mandate equal treatment in the playoff for all conferences the people who actually run the playoff would laugh at them. But of course the NCAA will never do any such thing, because there is nothing that would bring an end to the NCAA faster than the NCAA trying to tell the big time college football schools how they have to run college football.