I had exactly the same feeling as you after reading the article. And interestingly, all production parsers for all major languages are hand-written recursive descent parsers. On the other hand, if you inspect the actual code for these production parsers (even for newer languages like Swift, Scala, Kotlin, or Rust), the complexity and amount of code is still quite staggering.

Isn't a large portion of the code to get friendlier messages for the user?