For me, ROTJ was only hurt by the prequels by them adding things like Hayden, the Jedi Temple, and Naboo into it. But if you simply take the real ROTJ, I think it's the other way around, that it hurts the prequels, especially ROTS, by telling how things were supposed to be then going back and contradicting it. But of course you could say, and I would say, that they hurt themselves that way by not sticking to the story.