In some ways, I agree. Many physicists, neuroscientists, and philosophers believe there is no free will. Their arguments are persuasive to me, and I defer to their expertise. (I believe, however, that the illusion and language of free will remain important in daily life.) And I, too, would prefer to inflict "punishment" only as a deterrent, when there is no other method for correcting behavior; I dislike the idea of retribution. And I see that beings can be deterred even when they don't have free will. We can influence the behavior of robots...of insects, fish, rats....and of humans.
But here is my question: If there is no such thing as ethical responsibility, then why "ought" people interfere with others' behavior? We can try to interfere if we like...but then, I suppose, whatever we ultimately do, we were pre-determined to do. I guess it collapses into the question of: Doesn't recognizing afreeism lead to total apathy, a passive wait-and-see how everything plays out according to predestination? Why should we care about questions like motives and goals for punishment (e.g. deterrent or retributive) if we can't control whether we punish someone else or how they will react to being punished?