For everyone who is currently loosing productivity, perhaps your time might be well spent reviewing `git daemon`: http://git-scm.com/book/en/v2/Git-on-the-Server-Git-Daemon
I don't use github because it gives me a git daemon. I use it because the interface allows me interact with non-technical people when dealing with code and resources. I use github because, even though it is down right now, my stuff is backed up, I don't have to deal with the nitty gritty of ensuring backups succeed, I don't have to deal with the system when it goes down - someone else does that for me. Hence I would never want to run a local github clone.
Arguably you should be able to mirror on both an internal git repository somewhere, but GitHub is down infrequently enough that it's hard to justify that work + continuing costs if you don't have your own hardware + security patching + other admin costs to managers until you see multiple outages in a small enough window.
It doesn't matter what kind of deployment you do. Even s3 has outages if the network between you and s3 bites the dust. Even if you deploy straight from the developer's workstation to the production server, you can have an outage - network splits, hardware failure, developer-with-commit-rights gets sick. Working around an outage means you're not working on the product, and that's a loss of productivity.
Assuming that we're talking about things which are already stored in Git and not e.g. an HD video collection, what would make your original statement true?
With a ton of projects now hosted on github, github being down is a major dent in my overall productivity even though we _do_ have an internal git server.