I agree with you and I think the question itself might be putting the cart before the horse. We didn't develop moral philosophy so that we could punish murderer

I agree with you and I think the question itself might be putting the cart before the horse. We didn't develop moral philosophy so that we could punish murderers, we started punishing murderers first because we had to and then we started thinking about how to communicate the rules and navigate the fuzzy grey areas. It may be that free will is a philosophical dead-end but if you get rid of it then it turns out it was never all that foundational to begin with.