There are other groups too. Like Big Rich Daddy who wants his kid to go to Yale as a legacy but he only has a 26 ACT and has only donated like $1m. When test scores are required, top schools basically have a “budget” of 25% of their student body they can admit with any score without it adversely affecting college rankings. Making tests optional makes it easier to admit more students that don’t “meet the bar” otherwise, since they don’t count against the 25% quota.