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Shadilay my brothers and sisters. With any luck we will throw off the shackles of normie oppression. We have nothing to lose but our chains! Praise Kek!
THE MOTTO IS "IN KEK WE TRUST"
You don't get to just decide when to include and exclude fights. I see nothing, still, that makes me think Vader didn't fight to the fullest of his capabilities. If anything, his constant training and improvement after ANH shows that even he thought that he wasn't performing as well as he should have.
A) Jedi aren't in the habit of crushing people into balls. Just because you "can" crush someone into a ball doesn't mean you "should."
B) Sith have no moral qualms, but they are usually arrogant, especially against non-Force-users. This often leads to the non-Force-user getting the upper hand.
Consider Vader vs. Boba Fett. Vader knew he could crush him anytime so he toyed with him a bit. This allowed Fett to get in a good shot. Vader then went "no more playing around" and started crushing him with the Force.
C) Not every Jedi/Sith CAN crush someone into a ball. I'm pretty sure say, Johun Othone, wasn't strong enough for that.