It may be the subversive part of my mind working, but it occurred to me that someone of malign intent could print harmful material in this way. Obviously, the internet allows quick and free dissemination of information, but hard copies of training manuals for terrorist activities and paedophilia literature are sought after. Just recently, in the U.K., a would-be bomber was arrested and was found to have a hard copy of the Anarchist's Cookbook among his timers, chemicals and weaponry.
I wonder how much the librarians check on what their printing machine is being used for...