My guess is it's because the moderators have never considered creating a secondary collection of works for people to repost it to, as yes it's a LJ based competition (an indeed existed before the Ao3 did IIRC).

However, you can add the tag community: blindgo (it should come up as a autocomplete) to unofficially group works together: http://archiveofourown.org/tags/Community:%20blind_go/works