While I agree with this point of view more than the one that causes the pointless unproductive flamewars we've seen far too much of, one doesn't always have the

While I agree with this point of view more than the one that causes the pointless unproductive flamewars we've seen far too much of, one doesn't always have the choice of using what one likes. If you're comfortable with Git tools/workflow, and a project that you'd like to join the development of is using Mercurial (or vice-versa), that creates a slightly higher barrier of entry. Even given tools to allow a large degree of interoperability, you'll still (so far) be referring to commits by different ids and such. Sure, it's minor, but it's not entirely dismissable.