One thing that contributes is that the moderators of this forum have a policy (as far as I can tell), of being pretty pro-active in merging a new thread into old or existing threads and making "big" resource threads out of them.
A consequence is that the AA/AAdvantage front page is chock-a-block with wiki-threads. Everytime somebody asks a question where there's already a thread, one of the consolidated resource threads gets bumped.