The Donner party were a group on the Oregon trail that got stuck on a mountain pass in the winter and resorted to cannibalism to survive. The Dollup did a really good podcast episode about it.
Also the cafe in the University of Colorado UMC is named "The Alfred Packer Gill". Alfred Packer was a similar famed cannibal.
I guess its that the point of a National Forest is to conserve and take care of the environment, and making it a picnic ground is the opposite of doing that (with littering and all, I'd assume)