In Mercurial, you backup in case Mercurial does something it isn't supposed to do and you lose data. With Git, you backup because git is hard to reason about an

In Mercurial, you backup in case Mercurial does something it isn't supposed to do and you lose data. With Git, you backup because git is hard to reason about and there's a good chance that the command you're running will put you into a technically-valid state that you don't understand or know how to get out of and you don't want to spend hours Googling git jargon to figure out how to get out of it. This might be detached-head-state for beginners, or an odd rebase that somehow lost your data and your company's git experts can't figure out where it went. Obviously the probability of such a state is inversely proportional to your understanding of git.