Dude the majority of the members in ANBU are kage level. come on oro, danzo, kakashi, itachi, and maybe others that we dont even know about. wasnt minato and jiraiya in ANBUBy your logic the Anbu should have been at a Kage level or beyond it? because that's what the Akatsuki members are.
The Anbu are weaklings...both Asuma and Kakashi are Jouni, but they are not at the same level..just because Itachi and Orochimaru were in the organization doesn't mean they can be as strong as them.