Colleges may want some (but not too many) new frosh to start next spring to balance out the enrollment between semesters (normally, fall is more heavily enrolled because students who graduate a semester early or late usually have one extra fall semester compared to spring semesters). Since some colleges have previously been admitting fall applicants to start in the spring, they may welcome some number of extra deferrals.
But that may not work as well for colleges that offer many courses within sequences of prerequisites only once per year so that a student who starts in the spring may end up being delayed another semester in a critical prerequisite sequence.