If delegates are able to vote for whomever they wish, that would negate the whole purpose of presidential primaries.
Numerous ones from the GOP have been signaling they approve of heading in that direction — letting the Party determine the candidates and the nominee, and bypass state party primaries altogether.
That would give the little dictator-wannabes power to choose without being bothered by the commoners.
Binding primaries have only been more than an oddity since the ‘60s - ‘70s.