I sympathise with this point of view, but I think it misunderstands what Tarn is doing. DF is a weird (also fun and deeply rewarding) piece of outsider art. Source code is his medium, but expecting him to apply professional software engineering practices is like expecting Andy Warhol to use the same process as Campbell's when making the label for a soup can.

That's a really great way to look at it, thank you :)