Most research and observation, some dating back from the 1800's, differs with your conclusion.
Unless you consider a torturous, permanent and negative brain alteration to be a Ccnstitutional punishment, that is.
Well let’s see, the modern prison isn’t cold and dank; doesn’t have gruel to eat. The truth is that the modern version (in the US) of solitary is not some reenactment of Devil’s Island or The Man in the Iron Mask. These prisoners have access to books, music, reading material, writing material, law assists for their cases. They are fed and housed in temperature regulated facilities. Is it heaven??? No not at all. If you can’t do the time don’t do the crime. The people who end up in solitary are there because they are violent to either another prisoner or a guard.
I know someone who spent some serious time in Pelican Bay. He didn’t like it one bit BUT and this is the point he made up his mind to never go back. He has gotten his education. He has changed his life. Even he will tell you that this is what it took for a hardliner like him.
Now I am not saying everyone will do that. But those who want to can.
TORTURE??? Oh please a word thrown around all too frequently. Read Sholshetnizen’s Gulag and then tell me about torture.