'Course, author totally glossing over the fact katana only barely worked and were shaped the way they are solely to try and get a mildly decently usable sword out of some of the worst iron ore known to Man
Well no, that's not really true either. They were made the way they were because the ore wasn't great (but not totally shit either, other civilizations have also used iron sand), and because the smelting technology wasn't up to snuff, they couldn't fully melt the iron.
The shape has little to do with that, it's not like the shape is unseen outside of Japan, and there used to be many variations around, but after a point they seemed to standardize on that general type of slashing sword. And it is really good for slashing/cutting, and clearly served the purpose they had for it (backup self defense weapon in a context without heavy armor, with the occasional "punish the peasants" use case), otherwise they would have kept changing things.
And it's not like they're badly made, they did get really good at making them. Immensely good, even. Some of the masterworks given to shrines are works of art, and showcase incredible skill. Not having access to homogeneous steel did hurt them, but they focused on the good aspects of what they had to work with.
But they're absolutely not the end all, be all. From a western perspective they're an odd combination of features, but there are swords that can be quite similar in proportions in western and middle eastern areas as well. And most certainly there's nothing inherently superior about them vs. Western swords.