There has been so many interpretations of the joker even up to that point. To say "truly understood" is a joke in bad taste. At least the hill will get some fertilizer.

Dude had implants to make his face fuller

Hot-Take: Batman ‘89 is included in the adaptations that did not understand The Joker. But everyone had a different idea of him for some reason, therefore every adaptation is a little different. But I’d say Hamill’s Joker is probably the closest so far.