Group shunning is very destructive psychologically as we are all hardwired to belong to our "tribe" for the sake of survival. Shunning and ostracism in some communities even today can mean death for the one being chased off. That's why the threat of shunning is a very powerful psychological weapon that works very effectively. Science knows it. WT knows it. We know it.
So what it has accomplished is keep people in fear and in the compound.