Most people strongly disagree with you. You need to offer an argument, not an assertion, since you're callit for a major and unpopular change.
And if like many of my lefty friends by "abolish" you actually mean something that doesn't even come close to meaning "abolish", you're just causing problems with your abuse of language.
He didn't say anything about other punishment. There are many traditional punishments that have been used for thousands of years, some of which are still in use today. For example, the problem of shoplifting in Saudi Arabia is handled without incarceration. Maybe that is what he prefers.
If there isn't punishment, then nothing stops anybody from getting a group of friends together to dish out punishment. It'd be like Somalia. Eventually, if the group gets big and well-organized, it might be recognized internationally as the legitimate government.
That part is actually easy. We just send them to geowwy's neighborhood, so he could have the pleasure of getting stabbed or shot in the street for his wallet.
And if like many of my lefty friends by "abolish" you actually mean something that doesn't even come close to meaning "abolish", you're just causing problems with your abuse of language.