Playing conference-only games minimizes the pool of co-minglers. Now we've got ~30 (15 conference teams + their 15 OOC teams) groups potentially exchanging the virus. With a normal schedule, that goes up to ~75 (15 conference teams + their 4ish OOC teams).

As well, playing conference-only theoretically means a tighter travel footprint (see the conference's requirement that the OOC game be in-state). Witness our team's complete lack of plane rides this year (IIRC). Once again, less opportunity for exposure and mingling.

It is of course not 100% perfect. The only 100% perfect remedy is to not play the season, which, as we regularly get reminded around here, would have a huge economic impact, and basically be the end of the American Experiment.