The decision not to play was based on medical and scientific evidence. That 3 conferences choose to play is their decision. However, like amy well planned game or fight, once to first punch is thrown, all plans are revised. It's okay for the professionals to be in a bubble and play in that bubble. However, college students are not professionals, they are students. they have classes,, they mingle, they have parties (don't tell me they will all be choirboys) so the risk of spread is real. Because nearly half of all spread is via asymptomatic people, the presence of symptoms can't be a guide. If these athletes (sorry, STUDENT athletes) are tested every day to insure their safety, how about the rest of the campus getting the same care? But to answer the question, what would be the worst result or catastrophe? If players came down with the COVID with lethal results. If they fulfill the season successfully, good for them. Playing a spring season and then a fall season would be catastrophic because there would be no time to heal and then practice in preparation for the next season.
But to paraphrase a prior comment, there are too many other important issues in play than to worry about the catastrophe of a successful football season for other conferences.