Well, it mentions XSane because that is the complex beast that Simple Scan is meant to simplify, and GNOME Scan because readers might wonder why a GNOME scanning project wasn't based on it.
It's obvious that this article isn't what you were looking for, which is unfortunate, but it did set out to be a "look at Simple Scan". Given that, it seems like it covers the subject. There certainly is no systematic attempt to only cover GNOME tools or anything of that sort.
As always, though, the comments make a good place to point out other tools that do the same, or a similar, job.
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