[pm90]

It came up as a consequence of the criminal justice system. That kind of punishment was meant for people who could not be left by themselves as they posed a very real threat to society: murderers, rapists, arsonists etc. Once the system is in place, its easy to just "add" to it. Making certain things severely punishable (e.g. the prosecution of Aaron Schwartz) just requires the lawmakers to categorize these new crimes in a certain way and not to invent the category itself.

Of course, if you go back further, punishments were invented by the ruling class to keep everyone else in line. The king could pretty much have anyone hanged if he wanted to and it took sometime before there were enough smart people in society to suggest that this was maybe not the best way to live.