If a man convinces 100 others to take up arms and commit violence, who is to blame? The pen, loudspeaker, or the internet?
Tools and technology are not living beings. They have no moral values nor duty, and can be used to achieve both great or terrible things.
Banning things simply for being used in a crime is an emotional reaction. But it's easy, and it feels good. However, it distracts from addressing the actual cause and actors behind crime. "Judging" an object on a scale of good or bad, based on what it has been used for is an inaccurate and unfair measure of its worth. The historical record of what something has been used for is a reflection of its users, not the object itself.
There is quite a difference between banning people from possessing something, because people are dangerous/irresponsible, vs banning something because its very existence is "evil".
Only Furbys are truly evil.
@jkn
Culture on an online forum is a function of precedence and site engineering, not chance. The majority of school shooters several years ago spent a majority of their time on anonymous image boards like 4chan. Would you stand by while violent contagion grips a nation(see: civil war), or would you actually do something about it?