The shunning and disfellowshipping policy can also be compared to 'stoning', especiall clear in the story of the adulteress brought before Christ to be stoned. The letter of the law stated that an adulteress is to be stoned. Yet Christ forgave her... and said that he who is without sin could cast the first stone.
The WTS promotes a 'letter of the law' and forgets all about mercy, which is the greater thing.
And just as he who is without sin could cast the first stone (and none could of course), then a witness should consider that he who is without sin can commit the first act of shunning. Or marking. Or any of the other things that they do to punish one another.
Peace,
Tammy