I don't know a single tool in that list outside of tangential experience with Ruby. I've worked in some combination of Java, Objective C, C#/VB, PHP, Python and several types of SQL over the last decade. I would hardly call myself a beginner. It doesn't mean this tutorial isn't useful, just that it's only useful for the extremely small subset of developers who happen to use Ruby, HAML, SASS, and CoffeeScript.
Perhaps not. But it seems like the author added an unnecessary level of abstraction for parts of the tutorial. It's his tutorial - he can do what he wants ... but it likely slows, complicates, or excludes-from-participating-in people that aren't well-versed in his chosen toolkit of technologies.
