So tell me something, just who was Luke’s equal in the dark side in the OT? As one rises in one side of the force, another rises on the opposite side, right? It couldn’t have been Vader, he rose to power a lot early in the PT and he didn’t get more powerful as Luke got more powerful. Also if that idea is true, there should have been a lot more dark jedis around during the PT, one for every jedi.

In ESB, Obiwan says that if Luke goes to face Vader he will face him alone, “I can not help you”. But look what Yoda did in TLJ. Sure seems like Obiwan could have lent a hand now.