This becomes more significant when you consider that software binaries (not just source code, actual ones and zeros) are copyrightable. Copyleft licenses like G

This becomes more significant when you consider that software binaries (not just source code, actual ones and zeros) are copyrightable. Copyleft licenses like GNU GPL make use of this by requiring distributors of binaries derived from other GPL works to also release the source code of those derived binaries to the public. However, in the hardware world you could take a open PCB design, modify it, and distribute the physical PCBs or use it in your products without having to publicly release the PCB schematics as well.