I'm not sure. If software copyright didn't exist, then source code would still be treated as trade secret. Code obfuscation would be used to make reverse engine

I'm not sure. If software copyright didn't exist, then source code would still be treated as trade secret. Code obfuscation would be used to make reverse engineering harder and source code wouldn't be provided, which is not a lot of change for proprietary software. In addition, copyleft and free software attributions would not exist without a framework of enforcment. A clear loss for free software. Free software, apart from some very permissive licenses, requires copyright to exist.