Well, yes and no. You're right, if you are contributing to a project, you likely won't be initializing many new repos... however, the tutorial does show which git commands are common, and their basic use-cases.
Such as:
git status
git add
git commit
git branch
git checkout
git log
git reset
git merge
git pull
git push
When working with an Ignite repo on Github, after forking, the usual workflow commonly involves making new local branches, tracking changes and new files, committing and merging back into your fork's master branch, from which you likely will issue a pull request.
These commands are really central to using Git. The tutorial will not make you a Git Wizard, and if you are familiar with Git already, there's not much you will take away. But, we do have a lot of new members in the community, so spending a few minutes to learn some basics isn't too bad 