I understand your point-of-view but I just gave a real situation in which counting down the clock adversely effected the outcome of the match. The main point of the assistant is to be able to see those calls that happen away from the head official, or offer an opinion on a call if the head coach or head official requests it. Yes counting down the clock is also part of his duty.
I'm just saying it would be nice to definitively say the assist MUST count down but there are situations where it would be more pertinent for the official to keep his eye on the action rather than count the clock. I'm pretty sure the coach of the kid that lost the match I talked about would have the opposite opinion of yours. But to be honest, this is something my opinion waivered on when I was officiating. Do I only count or do I count when visually feasible to not distract from the action on the mat? Because I was burned.