2019... so what?
Chemistry didn't change a lot in the last two years, thus such an article is as good as it had been published yesterday.
Chemistry didn't change a lot in the last two years, thus such an article is as good as it had been published yesterday.
But we don't need such nitpicking for articles on more stable arguments.
... right, that is the reason for putting the year in titles ...
Or maybe it's done so that you can quickly discern whether it's old news, or a new development of something you've heard about previously.