>>214042607
I'm not sure now that the old EU lore all got tossed out, but that was originally the idea yeah
Vader getting crippled stopped him from ever reaching his full potential, which was greater than Palpatine for sure. Palps even says it himself in the movie to Yoda - "vader will become stronger than both of us"
That's why palpatine was so pissed off about the whole situation. His perfect successor that he'd groomed to become the most powerful beign in history got reduced to a fraction of what he should be trapped in an iron lung
However, even crippled, Vader was still the strongest guy he could possibly find to be his #2. So he was stuck with him, and Vader was stuck with Palps too because he had literally nothing else to live for.
A rule of 2 where the pupil can never surpass the master, definitely not ideal. That's why Palps jumped at Luke immediately to replace Vader
The exact figure of Vader only being 80% of Palpatine's strength supposedly comes from George Lucas himself but I've never seen it properly sourced