> Surely there are other, equally pragmatic and sensible, documents? (I admit that I don't have any examples, but I am not often exposed to good or bad procedures documents.) Why does this one deserve particularly to be singled out?

Because its good enough to serve as an example, and the author was familiar with it? If there are many equally good examples, and there is value in an example, then there doesn't need to be anything above the other alternatives (and, if they are equally good, there won't be, by definition) to select a particular one -- doing so at random, or by aesthetic preference unrelated to the function is fine.