Maybe that's where we're getting hung up here. I am still calling it teaching if it is not "new information" historically but new to those who are taught.
For sure there is no other gospel to be taught.
And I think there is a difference between keeping the command in Colossians 3:16 to teach and admonish one another, and calling yourself "rabbi" - everything God gives us is for the benefit of each other, to be shared and transmitted to one another in love. That doesn't mean to me that any of us are supposed to think of ourselves as gurus, or to treat some man or woman like they are - but we still should think of ourselves soberly, and recognize when we can learn from someone.