This idea only rings true if your team is reliant on a single infrastructure service you don't control.
If you maintain mirrors of your repos on multiple servers you control, or on multiple services run by others (eg GitHub + BitBucket) there is no issue when one suffers an outage.
Hell, git's built-in pull-request functionality works over email and doesn't require any specific git server.
I have issues with git specifically (I find mercurial is a better tool for most tasks) but GitHub/BitBucket/etc are not the definition of what dvcs is about.
If you maintain mirrors of your repos on multiple servers you control, or on multiple services run by others (eg GitHub + BitBucket) there is no issue when one suffers an outage.
Hell, git's built-in pull-request functionality works over email and doesn't require any specific git server.
I have issues with git specifically (I find mercurial is a better tool for most tasks) but GitHub/BitBucket/etc are not the definition of what dvcs is about.