Most look to be guides. Guides about xenforo. Those obviously are unable to show "favortism", as I am certain if an add-on not related to xF as a whole was added, there would be many questions as to why/how it is up there and <insert other developer> couldn't get theirs in.
As of right now, it will be guides that can help admins learn to use the software for reasons Paul posted. For now, that policy shall not change for now.