You can configure git-receive-pack to not allow ref deletes (receive.denyDeletes) or any ref updates which aren't fast-forwards (receive.denyNonFastForwards), which makes this kind of data loss impossible. With Gitolite you can even set this permission per-user per-branch (https://github.com/sitaramc/gitolite#_main_features) so that the great power is only given to those with the great responsibility to handle it.
Of course, somebody still has to know and care enough to want to tweak the default configuration, and it doesn't help with GitHub for the moment, but I wouldn't be surprised if they added finer-grained branch permissions in future.
Of course, somebody still has to know and care enough to want to tweak the default configuration, and it doesn't help with GitHub for the moment, but I wouldn't be surprised if they added finer-grained branch permissions in future.