The issue with having a 7 throw is the enormous stress it puts on the team. When your best scrounger is stuck to a sideline (as coaches don't want them running across the field) you lose your best defender and ball thief. You may recall Phil Kearns who scored tries wide out as he kept on that side of the field after throwing in. The AAGPS hooker has an enormous workload as the scrounger and hard runner who then backs ups with with throwing to a new line out to players who have yet to get in sync with the throws. He may be small but damn his heart is enormous.