The alternative is for individuals to inflict suffering on each other, which is just vigilantism and mob violence.
No, the alternative is to not apply retribution. To me anyone who applies retribution is nothing more than a thug, whether doing at the behest of the state or their own accord.
Ok. Now convince everyone else of that.
Plenty of people are convinced of that - it's pretty much the position the linked post is arguing against, for a reason.