Yeah, I was able to go to an early screening of Joker and Todd Phillips said that he followed the hero's journey right up until the end. For him, it was that Arthur didn't answer the final call to adventure. He rejected it and that's why it happens the way it does.
As to the question of Obi-wan not meeting Vader until A New Hope, Vader in that movie doesn't actually say when he saw him last. He say something like "Something I haven't felt since..." then just walks off.
Yeah, I was able to go to an early screening of Joker and Todd Phillips said that he followed the hero's journey right up until the end. For him, it was that Arthur didn't answer the final call to adventure. He rejected it and that's why it happens the way it does.
As to the question of Obi-wan not meeting Vader until A New Hope, Vader in that movie doesn't actually say when he saw him last. He say something like "Something I haven't felt since..." then just walks off.