system
Given the following post, respond as if you're commenting on Reddit:
human
[Star Wars] why do Yoga and Old Ben Kenobi try to get Luke to kill Vader and not the Emperor?

Just watching ROTJ and it occurred to me that Obi Wan and Yoda never pressure Luke into killing ol' Sheev but they have it in for Vader.  Obviously Anakin betrayed the order but why do they not tell him about the Emperor?
gpt
That is a genuinely good question and it is one that needs a multiple part answer.


* The jedi are blinded by their hate of the traitor Darth Vader, and they don't see him as redeemable


* The emperor sits on the throne while vader does the leg work, the jedi do not care about the rebellion so they 
think eliminating vader will do the most good.


* Becoming powerful enough to kill vader would be a big stepping stone to being powerful enough to kill the emperor.