Quote Originally Posted by DarthEnder View Post
Hell, Kushina's ghost was even still able to use jutsu against the Kyuubi, despite her being, you know...dead.
Yeah, she did it for a short while, and then vanished due to using all of what was left of the chakra she had managed to leave behind. That hardly suggests some ghost who never intended to leave chakra behind could power a corporeal body again.

If you reckon the sacrifice has got nothing to do with powering the zombies, then why have the sacrifices in the first place? Just take the piece of tissue containing the DNA and be done with the summoning. No need to secure a human to consume in the technique. The very fact it does require somebody to sacrifice tells me that's where the power is drawn.