The Git project has a patch submission process that's unfamilar to the majority of Git users. Any potential contributor—wanting to fix a small bug, or tweak documentation to make it more friendly—will learn that mailing a patch is not as simple as you might expect, especially if they're using a webmail service, like Gmail. The recommended approach is to forgo regular email clients, and use git-format-patch and git-send-email on the command-line to ensure nothing gets lost or auto-bounced (for containing HTML, for instance, which Gmail does by default).

This might change in the future, but for the moment, the core Git contributors have decided to keep patch review where it is, on the mailing list, and won't be reviewing, for instance, GitHub or Bitbucket pull requests.

submitGit is a small step in trying to make patch submission easier. If you create a pull request on github.com/git/git/, submitGit can send it to the mailing list for you, correctly formatting the patches. The discussion stays where it is—on the list—but at least that initial step is a little easier.