. . . or keep them from going down (and dropping from the rankings).
Given that too many people focus on USNews rankings, pretty much almost all the LACs (and other schools in rural and/or decreasing HS population areas) and the top publics (who have a mandate to take in kids from all demographics and geographical areas of a state so typically don’t focus on test scores as much) have an incentive to go test-optional. Also any schools that want to game the USNews rankings more heavily.