To be fair the the grandparent, the difference between immutable data structures and final variables in imperative languages is large and fundamental. If the author is (and I don't know, because I haven't read the article recently) making this analogy then it is going to be extremely confusing for some people.
The article doesn't make this analogy, that was my point. It doesn't really delve into immutable data structures at all, and just discusses FP in broad strokes. This isn't really a bad thing, since I don't think it was meant to be a deeply technical article.
