So Few Schools With >75% Yield - Lots OF People Reject Ivies?

We can argue all day about which policy favors yield more for which school etc, but I really don’t understand this obsession with yield which apparently the best of the best also seem to have. With so many more qualified applicants for each of the spots they offer, surely they can afford to lose many more without compromising anything. I wonder if there is anything we parents can do so they stop playing games.