Earlier quoted context omitted.
Web services go down. It happens. You make the choice to use them anyway. In this case, Github is very responsive about outages and clearly strives to eliminate or reduce them as much as possible.
And sometimes web services go down for good. Again, this is an understood tradeoff, and I'm not arguing that. What I do argue with is that "git is distributed" does not cancel out this particular tradeoff, which I'd the statement that was made by the person I am responding to. An actual solution used by many other services is "let me use my own hostnames with this service", which GitHub does not support for your repo…
You can't really fault Github for individual teams not opting to host their code in more than one spot online, even if Github doesn't offer the capability for users to use their own domain name for seamless switching of git hosts.
Does Github encourage keeping everything centered at Github? Perhaps implicitly. But they certainly don't lock anyone's data in, so blaming them for their customers opting to NOT put their code anywhere besides Github seems unfair.