For me, just a small amount of information in the RotJ novelisation (also present in the script, but cut from the final film) pretty much kills the entire prequel story and exposes it as nonsensical.

Ben tells Luke, "When your father left, he didn't know your mother was pregnant."

Just think about that for a second. Anakin Skywalker didn't know his wife was pregnant. That one sentence negates everything that happens in the entire movie of RotS. No visions of her dying in childbirth, no trying to make people live forever, no faux-Faustian deal with the devil. Just straight up selfishness and going to the dark side completely for his own reasons.

He goes on to say that Anakin's wife went to live on Alderaan but gave Leia to the Organa family to conceal her identity. She thereafter died of unknown causes, presumably around three or four years later.

You could argue that this doesn't really "count" since it was cut from the film itself, but I quite liked the RotJ novel and always considered this information as gospel when I was growing up. Also, viewed this way, the story as presented in RotJ makes perfect sense, since this was the backstory they had in mind while making it. That the prequels contradicted it so thoroughly was pretty much the last straw as far as hoping the whole thing would make any sense, and the only way to resolve this is to declare that the entirety of Episodes 1, 2, and 3 are essentially very expensive but badly-conceived fan fiction, which have nothing to do with the true story in any way. (Except in this case, the 'fan' who made them was actually the original creator, but that's what it's come to now.)

Therefore to maintain integrity it is best to shun them and pretend they don't exist.