It’s very simple to understand. P5/4 football is both much better than H5 football and much more popular with a much larger fan base. The CFP is designed to get the “best” teams into a playoff with 12 teams.
There is a committee with published guidelines on how the selections are made.
This is logical and profitable.
Then there is the lonely opposition fighting a fight on a message board where there is very limited interest. The opposition’s only option now is to start an insurgency. Good luck organizing the insurgents.