Creating the Chosen One Prophecy, saying that Anakin was destined to destroy the Sith, and thus creating the conditions for the Sith not to return after Return of the Jedi, is the best retcon that was ever introduced to Star Wars. Putting a limit on the Sith’s ability to return after Return of the Jedi forces the writers to come up with original, more interesting villains instead of reusing the Sith over and over again. And that is good, especially when you consider that the Sith have often similar reasons for turning to the Dark Side (they are all selfish and want power), which often results in the Sith being very similar to each other, which is boring. Too bad no one cared about this limit neither in Legends or Canon.