This is good advice for Zed's LxTHW brand, because those books are geared toward learning one particular language at a time. But in some contexts having an integrated approach can be an advantage. Readers of the Ruby on Rails Tutorial often tell me that they didn't really "get" web development until they saw how Git, GitHub, Heroku, and Rails all fit together. That's because the goal of the book isn't to teach Rails; it's to teach web development with Rails. Unfortunately, this means that some readers are overwhelmed by all the detail (and I may someday make a product to better meet their needs), but for many readers seeing the whole picture is a revelation.
frankly speaking, whenever I drop into a tutorial and it begins with an introduction to github or vim, I leave the page. it's because it shows the author isn't focused on solving my problem which is I am not familiar with some specific technology, he prefers to advertise his favorite tools for some reason and lock me in his way of doing things. just show me what I'm looking for, I will figure out the rest myself if I need it.
You're missing the forest for the trees. While it's true that those particular technologies aren't necessary, professional-grade development does require version control, shareable repositories, and deployment. Git, GitHub, and Heroku are just the solutions I happen to use in the book.