You basically just corrected Mike89's statement - in that it's better energy applied down range at the target.
So that last sentence should have read: "Having the correct spine allows a more efficient transfer of energy from bow to target."
It's a very technical and subtle difference in wording, I know. But it is a very important concept to understand, regardless of whether you know the correct technical terms. Otherwise it will screw up your understanding of the interaction between the bow and arrow.