mixture, exactly how much support does closed source give to the average home user, or small office user? None, aside form patches and opens source does exactly that too.
Two words .... Linker Libraries.
You see, *nix/*nux systems nothing but a collection of software. You've got the kernel and you've got all the third-party software. All this jumble of software is developed and patched up by individual groups of people. There is no real overall picture despite what certain distributions might try to portray.
What that means is if you've got software on your Linux box that was compiled against, say version 0.9 of the OpenSSL libraries, but then your next patch pull from the Linux Distribution updates the OpenSSL libraries to 1.0, which breaks your software.
On the other hand, with closed source, the Operating System developer makes APIs available to third-party software developers. As the Operating System manufacturer patches and enhances their Operating System, they ensure as part of the QA process that the APIs still work as advertised.