Spring starts are about money, pure and simple. Empty seats happen because kids drop out, go abroad, or take medical leaves. An empty seat means no revenue. An empty seat means one less alumni to potentially donate to the endowment later on. Colleges - even tippy tops - want to avoid that whenever they can.
So they accept a handful of spring admits.
IF those admits are somehow less qualified (and I don’t believe they necessarily are) then withholding their stats is merely a perk to the college, not the primary reason for making these kids wait.