If you don't know the language, and it's different from what you know, it may look incomprehensible to you whether it's complex or not.

For example, the Korean alphabet is pretty simple, and the spelling is simpler than English, but to English speakers it can look intimidating, like hundreds of blocks of unrecognizable squiggles.

The article (over)uses macros, which make the code look more convoluted than it really is. The macro-by-example syntax is conceptually simple, but it has a punctuation-heavy syntax that may look alien if you don't know what you're looking at. BTW, this macro system has been originally designed for JavaScript, which is why even in Rust it looks odd by Rust's standards.