Most legacy code is this way unfortunately. The actual techniques employed by the "called out" code are not uncommon. I don't think that people are defending the lack of clarity but rather what the code is doing itself. It could be written more clearly, though one could argue that the lengthy series of articles does just that. Maybe it's an exercise for you to write it how you want.

Have you taken a look at some major C codebases? It's not justification but an appeal to authority seems pretty unnecessary :)