What if the pilot exceeds 10 points in downgrades instead of a mandatory zero manuever? One judge may observe different downgrades than another judge, and therefore yield two different scores with one being a zero and not the other.
Very easy, the judge that made it to a 0 by deductions discusses it with the 2nd judge. Either the 2nd judge agrees, or points out the other judges fault. Either way, you will not get out of balance judging ( one gives a 0 and one gives a 7).
I have seen odd scores many times when inputing scores for a contest. I have seen spreads where one judge gives a 10 and the other gives a 0. The contestant actually flew the wrong manuver, judge 1 scored it a 10 and the second judge caught the wrong manuver.
Having said that, I myself believe that confiring on 0's is a good thing and wish it was done in pattern. I look at it as a way to help new or inexperienced judges learn and progress.
In the end, it really doesn't matter to me either way. This is my hobby. I see no need to get stressed out over an imperfect system. Most times the winners of a class are in the right order at the end.