Right, but then you have to immediately re-test everyone - every player, coach, support staff, etc. And I'd wait 3 weeks, with multiple clean tests before introducing them back with the team.
So we'd potentially have teams playing without random groupings of players. If your team loses its QB and stud DT in a weak section of the schedule, cool. Or if you lose a backup center and your 5th CB, so what? But say you have a position group that has an outbreak - your whole starting D-line and 2 backups are out....wtf? Or they're out 2 weeks earlier, but are held out of a huge game, waiting on another test to come back clean.
Or of the thousands of FBS players, 3 die. Is football worth it then? We're back to the economy vs lives conundrum.