That was around in the early days of the archive, but it hasn't been updated in
years. I don't think there were more than 500 stories on the archive when it was last updated, and we're approaching the 3000 mark now!
Or... looking at the page again, the Fairy Tales challenge category was added more recently (only a few years ago), and I believe the Stories in Other Languages section is updated as new ones come in. But I don't think the other ones have been updated any time this millennium. In fact, glancing through a couple of categories, I see that most of the stories there predate the archive header system and don't even have dates on them.
But... The idea is still there. One of the things the archive keyword project is designed to do is replace the themes page. If you check the
fic database , you'll see that each story gets up to four theme keywords which cover most of the theme categories on the page you saw as well as a bunch of new ones.