Anki and spaced-repetition in general are a very effective revision system; posts that offer you a pre-made very effective revision system for better remembering LessWrong seems to me like they should on be on the main page.
I see your point, which I didn't before. I'm still not entirely swayed---a post on how to use spaced repetition well would definitely belong on the main page, but decks on specific topics seem important but not top-level to me.
The decks posted that reference a single post or sequence seem like they would best be placed in those actual posts, though that's not something someone other than the author can do. Second to that, I feel like they are better off in the comments to those posts or in the discussion section.
This deck, being independent of such a post, maybe does belong here, so I'm not sure why it seems so out of place to me.
Followup to: Spaced Repetition Database for A Human's Guide to Words
There's a great list of cognitive biases and fallacies on Wikipedia. For those who wish to aid their learning with some Anki cards, I've shared a deck. Just search "biases" in Anki.
For those who use a different program, here are the cards in a tab-separated file.
I'll soon update it to also contain the list of memory biases.