The line “once you start down the dark path, forever will it dominate your destiny” is also misinterpreted. Yoda isn’t saying literally any time you get angry or use the Force in anger, you’re beyond hope or redemption. … The consequences of your actions will still be there.
I don’t agree. The full line is “Once you start down the dark path, forever will it dominate your destiny. Consume you, it will! As it did Obi-Wan’s apprentice.”
Specifically look at Yoda’s usage of the word “consume”. Your actions and your decision making will eventually be completely affected by the dark side. It isn’t just that your life is marred by the consequences of your actions, although it is that too, he’s saying that you can’t just dip your toes in the dark side. It’s something that’ll pull you further and further in.
After Return of the Jedi, there’s irony in referring to Darth Vader because he does return to the light. But Darth Vader is, at this point in the story, fully committed to evil. Yoda brings him up to emphasize that once you turn to the dark side, you inevitably become like Darth Vader.
I’ve ranted about this many times before, but Yoda and Obi Wan were not telling Luke to kill Vader.
Luke: “I can’t kill my own father.”
Obi-Wan: “Then the Emperor has already won.”
Yes, and Yoda was right.
I addressed that already. Obi Wan is saying that Luke has to be willing to kill Vader, but he’s not sending him to kill Vader, as that would be pointless. The word they use is confront. I already posted this somewhere else but there’s a quote from one of the Timothy Zahn books where Luke talks about this, he says that he assumed that when they told him to confront Vader that that meant he would have to kill him, but that was wrong and that wasn’t necessarily what they meant. Not that that is Disney canon or G canon, but it shows that before the prequels that was the normal interpretation.