This is to make good data security practices. It often isn’t a good idea to store data in the repo, which might be public (or easily make public). This is also true of your SAS data files and your .Rdata. Be careful where things are stored. Sharing is awesome…until it isn’t.
Note, there are other ways around this using .gitignore files. But, we made the choice to not introduce that feature in this class. If you want to know more Instructor Matt will happily help you.