That seems like the new "reason" -- at least it's more valid than the old reason of "stopping gambling". There was a documentary, Netflix maybe?, where guards would routinely do sweeps and find any game pieces that prisoners has made - paper folded to make dice, notes and score sheets for D&D, etc
The problem is that they're not only deciding for themselves, they're also deciding for their cellmates, and anyone else they will be in close contact with (which, in a prison, is likely "everyone")
How a system so unjust can exist in a modern “democracy” is beyond me.