I find this a perplexing comment in view of the fact that almost all of the linked article is in fact about how the author wrote his own date parsing library; the "never do it" bit is just a couple of lines at the start and so far as I can tell is mostly there for fun.

(In particular, at no point does the article actually argue for not writing your own date parsing library. It just says, in essence, "Never do it. I did it. Here's what I did and why.")