But Apple has done exactly that. The core (Darwin) is open-source since the beginning - but other newer parts are open-source too. A great example is Grand Cent

But Apple has done exactly that. The core (Darwin) is open-source since the beginning - but other newer parts are open-source too. A great example is Grand Central Dispatch[1] which Apple open-sourced and has been since ported to FreeBSD. Another example is launchd, a replacement init system, that was open-sourced too. Even if they didn't do any of this though, it's silly to treat proprietary software as if it doesn't exist and doesn't provide any benefit. Personally, I would be thrilled if Apple (or any other company) used any of my open-source work, even if they made a proprietary fork, because as a result I'd end up with a better OS. Yes, it would be even better if they stayed open-source and contributed back - but if that's not going to happen, I'd rather software, whether open or proprietary, keeps on improving. If a proprietary fork is what it takes, so be it. Some of my favourite and most useful software is proprietary but contains open-source libraries. If those libraries restricted the use to only open-source applications, and the developers were unwilling to open-source, those applications might not exist - or at least might not be as good. If that were the case, we'd all have lost out. [1] https://en.wikipedia.org/wiki/Grand_Central_Dispatch https://en.wikipedia.org/wiki/Grand_Central_Dispatch