Star Wars

Honestly, that comes down to philosophy. The Sith are about domination. You gain power through fear and anger. They don't understand anything else. So they rule based on their philosophy. Also, in Lucas' vision, creating the Empire was to spread fear through the populace. That fear would reinforce the Dark Side and make the Sith stronger. Every time you have some person get angry and kill another person, or a family scared for their lives, it adds to the Dark Side's power. It's a metaphysical reinforcement of Sith ideas that make it impossible for Luke to really stand up to Palpatine. But the Jedi way is not to fight using power, but to embrace others as they are. When Luke accepts his father and himself as they are, he becomes a full Jedi and his father sees what he thought was impossible: that getting angry and accessing the Dark Side is NOT a permanent pathway to doom. You can CHANGE YOUR PATH and try to atone for your sins. Being a Jedi is about the idea that NOTHING is absolute. This is why Obi-wan and Yoda fail and Luke succeeds, he is the only person to try to change and improve and not see the Dark Side as a permanent hell but something to be overcome. (This also makes the Luke we see in TLJ nearly impossible to support, he's undone learning that cost him nearly everything to earn in such a silly way, it's practically unbelievable.)