I imagine github as an iceburg. Sure, I see things like bootstrap with XXXk followers and jquery on there. Big projects! Big names! Big! Big! Big!
But what about what I don't see? How many thousands of users have private accounts? How many thousands of businesses have private github repos? I don't really know. It's a smart bet that every time somebody sees all the prestige of the big name projects, they think "Hmmm, this is really working for them; Could it work so well for me/my project/my startup/ my enterprise? I hope I can make this private."
I am just saying, sure there is a lot of shovel selling going on. But just because you can't see others digging, doesn't mean they aren't out there.
This is the least transparent reasoning I've seen in a long time.
But it may have been (they hint at this) that they didn't need or want the funding so much as to have AH invested in the company. Taking their investment may create something of a partnership and gives them access to AH's advice/rolodex and encourages future support. It also gives them a concrete valuation to cite down the road.
Well, anyway I'm happy that Github is doing fine.
I.e. second leg of the current trend, when successful SaaS companies will offer products, which can be install on-premises.
In case of github it's Github for Your Firewall.