When there are multiple actors incentivized to ignore any history-rebasing. Of course if you're running your own git repo, you know your githashes will change i

When there are multiple actors incentivized to ignore any history-rebasing. Of course if you're running your own git repo, you know your githashes will change if you go back in history and change something, and it doesn't matter. When multiple people want to ensure that history hasn't changed, they can compare their hashes with yours, and have good evidence of who tampered with the history and ignore them / prosecute them.