>Rehabilitation IS societally useful.

This is very true. As an example, recidivism in Sweden is around 40%[0], compared to around 68%[1] in the states.

[0] - https://www.bra.se/bra-in-english/home/crime-and-statistics/...

[1] - https://www.bjs.gov/content/reentry/recidivism.cfm