I see. I honestly think that the no kill rule could work. It’s just that Gotham is so corrupt, the infrastructure and social support so lacking, that villains have no shot at rehabilitation, and every chance of just breaking out and doing it again. Joker has broken out hundreds if not thousands of times in every single iteration. If he got a secure cell without corrupt guards and actual help after the first insane murder plot, he could probably get better. I think in some iterations, he has, at least temporarily, improved significantly. I agree with the outdatedness. He comes from a time when kids were hit to “fix” left handedness. He’s going to use punching as a solution every time. It’s like if people started punching and emotionally abusing high support needs autistic kids instead of actually helping them. Y’know, like they used to. And still do. Punching might stop the behavior in the immediate future, but it’s going to get a hell of a lot worse than acting with empathy. Which, at least in the 90s animated series, he does tend to show a bit, with his always calling them by their names and the one time he comforted the woman that was stuck as a small child.