True, the example is simplistic, but that's just to make it fit within reasonable exposition.
The author has in the past shown (elsewhere) how his techniques can actually make dramatic differences in more concrete examples (he rose to some Internet fame for building a performant shell that could actually handle larger outputs orders of magnitude better than most available alternatives).
To me the interesting point is the reminder that there is an innate tension between going fast and being "clean" (i.e. maintanable/understandable). And once you are aware of it you can make your decisions in an informed way. Too often this tension is forgotten/ignored/dogmatically put to the back ("performance doesn't matter over cleanliness" and the likes).
Mind you, I'm also of the camp that performance is very secondary to cleanliness in modern enterprises, but I appreciate a reminder of just how much we are sacrificing on this altar.
Casey is a bit of a hardcore crusader on the topic, but I'd hardly call dogmatic someone who can provide you evidence and measurements backing their thesis.
The tests he put together here are hardly something I'd call a straw-man argument, they seem like reasonable simplification of real-cases.