Count me among the confused. Works are usually referenced by their publication year and, on Hacker News, I always assume something with a (YEAR) in the title was published in that year.

That seems strange, and the example you give is less applicable than one might first think.

A letter is private correspondence; the date it is written is essentially the date it is published. A manifesto, on the other hand, could be considered a public document, and so its date of publishing may not necessarily be the date it was written.

I get that it was written a while ago and only made available for public consumption recently. However, appending a date to the article name signals to most users that the article is an older article that may have been previously posted. This is the part that's confusing, and I think masks what is essentially a new document in the eyes of the public.