There are very few standards in the GNU/Linux world. GNU and Linux has, by themselves, become standards through ubiquity. POSIX is one, yes, but it's woefully inadequate when you've gotten used to all the bells and whistles any modern GNU/Linux distro puts on top of it by default.

And what about the BSDs? They certainly doesn't play well with Linux, or vice versa, but that's hardly an argument for calling either an agent for closedness.