Apparently because at the top levels, scrums were starting their push when they heard "yes 9".
No, I don't know why they could not simply tell the referees to penalise teams that pushed early.
No, I don't know why the matter was so urgent that it had to be actioned IMMEDIATELY (if not before).
Agree with your setiments entirely OB!
Some will recall that when this 'yes 9' instruction was introduced there was much debate about it being a temptation for the early push etc. There were even suggestions that the call should be so quiet that only the '9' can hear it - yes really!!!
A number of experienced props at grass roots level told me they thought it was a stupid instruction to give when props are poised to push. The suggestion they all gave me was to drop the instruction and let the 9 just put it in. Ref can always say to 'hold it' if not S&S.
But as we have seen, the top refs are incapable of penalising effectively for an early push (effective meaning it deters!) as they are of penalising for a crooked feed - and so the rules have changed - again! The crooked feed and no hooking at top level will no doubt continue - too many vested interests in front row gym monkies. Thank goodness at grass roots we are seeing refs insist on straight put in and long may they do so. Keep it up lads, maybe the top level will catch on? Or not...