>what good does it really do to prevent him from being able to function on the outside?

From whose perspective?

Part of the problem is that some powerful groups are incentived to keep people coming back to prison. Private prisons reap profits, politicians get an easy way to drive fear in their constituents, telcos can charge an arm and a leg for phone calls, commissaries clean up by charging exorbitant prices for toothpaste and ramen, etc.

Until we start connecting positive outcomes for those groups to positive outcomes for the prisoners, it'll always be an uphill battle.

As Upton Sinclair used to say, "It is difficult to get a man to understand something, when his salary depends on his not understanding it."