Ignoring the issues with public domain (that it doesn&#x27;t exist in many places, so the default you-cant-do-anything copyright rules apply), you misunderstand what I mean by freedom in perpetuity. If someone can take your code and make it proprietary (as well as adding some enticing features), your code is now used to take away users freedom -- even though your original code was free software.<p>Copyleft is the only defence against that form of attack on user freedom -- attack by distribution.