I don’t think that’s the goal or at least not a primary goal. I would say the main goal is to contain criminals so the rest of society can live without impact from their harmful actions. The second goal, for me at least, is to create consequences that are very real and difficult to bear, to deter other would-be criminals. The next goal down might be reform or rehabilitation, but as a taxpayer I am just as happy to contain the problem if it is cheaper to do so. I’m not sure I’m missing anything with the “zero productiveness” you’re talking about.