Which is why, in my neighbourhood, the Corrective Services Union usually objects strenuously whenever there’s a push to remove such “luxuries”.
Guarding prisoners ain’t much fun at the best of times. Guarding prisoners when they’re bored out of their minds is even less fun.
The prisoners will make their own distraction if they have to, and if the only way to relieve the boredom is a prison riot, that’s what you’ll get. Similarly, if the only compliance tool available to the guards is violence, then escalating brutality is what you’ll get.