Yes, exactly, so if that is the case then hasn't the author skipped over the most important part about the work. That being the process they went through to identify each of these functions purpose? aka: the actual RCE work?
This is kind of a pet peeve of mine with many RCE articles. They always seem to leave out the difficult parts. In that respect I view most of them as bragging rather than providing much in the way of a useful tutorial or learning material.
I'm assuming you're thinking about the functions that are named "DecodeRc4Key" and "XorDecode" and the like? I guess a lot of it is just reading the code (the disassembly, or the pseudo-C if your tool of choice can produce that), and possibly compare it mentally against things you've seen before, and/or to see how the data flows, to determine its purpose?
Also, in this article, it's more interesting to be learning about the overall structure of the malware piece, which algorithms are employed, and a small bonus about the c&c at the end. The author skips the usually boring details for us and presents a summary of his findings (xor, rc4, etc).
I'm sure there are other articles around that focus more on the low level mundane RCE work of actually identifying each subroutine, but that's not what this article is focused on. In fact, going further in the details about that here would have been a distraction, I think. On that note I agree the "...for dummies" headline is a bit of a stretch, though :)
This is kind of a pet peeve of mine with many RCE articles. They always seem to leave out the difficult parts. In that respect I view most of them as bragging rather than providing much in the way of a useful tutorial or learning material.