Even dogs have a pretty good sense that they've messed up when they do. Also it's proven that dogs understand if you recompensate other dogs more than them for the same task, and tend to stop obeying you in such conditions. Even animals have base morals, and so do we. The punch a baby argument increases in ridiculousness because I literally cannot think of one normal person who would consider something correct or even a good idea. You can't take simple actions like those and make them abstract like that, because you can "what-if" any ****ing thing in existance; human mind basically does that to the world to make sense of it, creating connections and valid logic not necessarily equates reasonable outcomes, often because logic cannot be applied purely to a series of real-world hypothesis.
For example, if theoretically, for there to be no crimes, it is a simple as no one commiting a crime, yet we see a completely different thing in the real world. To the extent social policy, crime rate and law enforcement are things that can be studied; for example: high income inequality always makes crime rise all over, so if you make social efforts to lower inequality, there's a strong tendence for crime rate to diminish, this is why Switzerland has an infinitely smaller crime rate than Brazil. The thing is, what translates meaningless logic arguments into functional philosophical thoughts is exactly that. For example, Socrates theorized that since things have an opposite (heat,cold;light,heavy;tall,short), it implies that if there's life, there's death, thus an afterlife of sorts. While an interesting argument that is presented in a perfectly logic way in Phaidon, I think, it's nevertheless impossible to apply for the real world, for the simple fact that different states do not exist in relation to each other, it is only such because we perceive it so, there's no tall, short, hot or cold, those are things based on our human perspective, but not-existant outside of it.
Very much like morals and what's right and wrong. It's true that they don't exist per se, but there are tangible good and bad things that can be done, even if most actions fall into some shade of grey.