They don't participate in the open source community. They're similar to Apple in that they take open source stuff and build a closed ecosystem on top of it.
GitHub has 6 pages of public repositories (https://github.com/github) that you can peruse. To pre-empt your response, yes, they aren't all open source projects that GitHub has released. But a great many of them are. Some of their popular projects include things like Atom, Hubot, Boxen, Linguist, and many more.
They also have developers who contribute to a great many other projects as part of their daily work; Ruby springs to mind - Aman Gupta and Charlie Somerville have contributed quite a lot. And they pay at least two people to work effectively full time on git itself.
But don't let facts get in the way of your rant.
The other projects are irrelevant, I'm talking about contributing to the core product they are vampiring off of.
You specifically said that GitHub does not participate in the open source community and I think I've amply demonstrated that you're incorrect. If you'd like to continue to argue the point, I'd appreciate some facts.
It's similar to Microsoft hiring a bunch of Linux developers to continue developing. Yeah, this is good for marketing checkboxes of 'supporting the open source community', but from the perspective of a developer in that community, it's worthless.
What would be nice is if they hired new developers to work on git so the community actually grows and gets something.
They are paying people who would otherwise work on Git in their spare time to work on it full time. That is a net win for everyone who uses git.
I'm going to give up at this point and just accept the fact that you're going to spin it such that any commercial entity that uses open source and doesn't open source their core product is a parasite. I think you're wrong, but you're certainly entitled to your opinion.
You're not entitled to your own facts, though.
These aren't my own facts. This is based on what I've seen with open source contributors for a long time. Rather than companies contributing code or their own engineers, they just hire an existing contributor to keep doing what they do. I'm not arguing that this is bad, I'm saying that they should be put on a pedestal for essentially throwing money at something that they depend on anyway.
I see I've struck a nerve with github fans, but be honest with yourself. Do we say oracle is a great open source contributor because they have java language devs?
Hell, the kernel is even open source. But it doesn't mean anything because their ecosystem is still closed.
Lots of companies throw money at some open source developers to continue developing what they were already doing. That doesn't make the company any more open source friendly. It just makes them a funding source for people doing the real work.
Contrast that with a company like Red Hat that bases everything on improving and supporting open source. People used to give them crap for RDO, but that's nothing compared to closed ecosystem github built on top of open source.
Github is just as supportive of open source as Stackoverflow (superficially). They just get a lot of credit by association for real open source products hosted on their platform.