GPLv3 and "copyleft" are not permissive licenses. They are copyleft licenses. MIT, BSD, etc. are permissive licenses. Aside from that, there is a considerable

GPLv3 and "copyleft" are not permissive licenses. They are copyleft licenses. MIT, BSD, etc. are permissive licenses. Aside from that, there is a considerable difference between public domain and 'freely licensed'. The latter involves an absolute nightmare of tracking down licenses and understanding the interactions between licenses, when working on a project of significant size (and influence). And licenses like the GPL make this even harder by being very restrictive. > Also the illegal file sharing has disrupted music massively. We now have so many songs you can listen to on Youtube for free. Imagine telling someone in 1990 you can listen to unlimited free music legally (albeit with ads!). The majority of music on Youtube is not there legally.