I strongly dispute this statement, and honestly find it baffling that you would claim as such.
The fact that you will be punished for murdering babies is BECAUSE it is morally bad, not the other way around! We didn't write down the laws/punishment for fun, we wrote the laws to match our moral systems! Or do you believe that we design our moral systems based on our laws of punishment? That is... quite a claim.
Your argument has the same structure as saying: "We don't need germ theory. The fact that washing your hands prevents disease is just one reason why you should wash your hands. People socially also find dirty hands disgusting, and avoid you as social punishment. Any reason you come up with for hand-washing works without a germ theory framing."
But germ theory is precisely why hand-washing prevents disease and why we evolved disgust responses to filth. Calling it "redundant" because we can list its downstream effects without naming it doesn't make the underlying framework unnecessary. It just means you're describing consequences while ignoring their cause. You can't explain why those consequences hold together coherently without it; the justified true belief comes from germ theory! (And don't try to gettier problem me on the concept of knowledge, this applies even if you don't use JTB to define knowledge.)