I just want to be absolutely clear...did you compare non-GPL licenses to slavery?
The south has even songs about the "good ol' days" where slaves was working in the field. Plantation owners clearly saw the change as oppression, and a limitation on their freedom to operate ones house and businesses as one pleases.
The societies we live in have answered that denying a little personal freedom in order to protect the collective offers more freedom than the one in which that doesn't happen. There's no debate about that. Then, why are we still debating this?