The default theme was, and still is, too bloated for learners to wrap their heads around. It has too many features, too many branches, and too many sub-templates extending the main template, due to the fact that it also needs to serve as a showcase for all of WordPress's features. I resorted to downloading the most minimalistic third-party theme that I could find, cleaned it up some more, and used it as a base for all the themes I've written since then.
I'm glad that someone finally made an open-source theme specifically for the purpose of being a rock-solid base for other themes. This is something that should have been done by the core developers 10 years ago. I don't know how much longer we'll have to suffer the sprawling spaghetti monster that WordPress is, but since a lot of us are stuck with it anyway, why not make our lives easier for the time being!
P.S. Please add a link to the GitHub repository, too. Some of us prefer git clones to tarballs.