BYU plays an FCS school regardless of whether or not they play Wyoming or New Mexico instead of Cincy and ECU.

In other words, when BYU was in the MWC, they played New Mexico and Wyoming AND Northeast Louisiana State and Northern Iowa and Idaho State. BYU plays FCS schools as often as they can (like most other schools). Saying 'Wyoming and New Mexico are better games than Wagner and Savannah State' is a false narrative and a red herring, because those games don't replace each other. Games with Fresno, Cincy, UConn and ECU replace those more typical MWC conference games.