Ironically, we have excellent examples of your ideas in practice. Video games from 1995 are lost to time because they cannot be legally duplicated and delivered and even if they were the os to run them is under copyright and no longer sold. Meanwhile, the source code to all MSFT oses before XP leaked and it hasn't hurt them at all. Might it hurt them a bit if DosBOX used that leaked code to make a better emulator? I don't see how, they're already no longer selling that code.