I disagree. I've always been under the impression that powerfeeding is when you force the snake to eat more than it wants to. Usually by hand feeding it another item as it's taking down the first. Where the idea that powerfeeding is letting the snake eat more than usual because it wants to came from, I have no idea.
Three or four mice would still probably only be 100 grams, which is a perfectly fine meal for an adult ball python.