The system is rigged against non-P5s, and even more rigged against independents not-named Notre Dame. It's not rigged against BYU per se. It's just that BYU is in the unusual position of being neither P5, nor G5, nor Notre Dame. It has to do with keeping money within the cartels, not with punishing BYU.
But have faith. In 2023 BYU will part of the college football cartels once again.