This is just the internal stuff, you DONT need to know this using git on a day to day basis. I use git for all my projects and most of the time, i mainly just type `git commit -a -m "lol message" && git push`.
Do you need to know everything about MS Word in order to become productive with it? No. Apply the same concept to Git or any software really.
I guess the difference is that if there's something that Word can do that I want to figure out, there's good Help and I can get pretty far by scanning the menus. With git, good help exists too (in the form of blog posts like this article), except that the concepts are significantly more complex than those involved in making automatically numbered chapter headings.
In short, to my experience figuring out how to do something non-trivial with Word is exploration. Figuring out how to do something non-trivial with Git is more like studying an advanced CS class.