What makes the Disfellowshipping and shunning so bad for the JWs is the way in which it is done.
The entire process is secret and the accused has no rights whatsoever.
If there is an accusation of wrongdoing against a person, the elders will form a judicial committee. This judicial committee asks as prosecutor, judge, and executioner.
The accused is not allowed to have any representation in most cases. In addition, the elders who serve on the committee while told they should keep things confidential often do not. (Wives have a way of getting information out of their husbands.)
The whole system is patently unfair and set up in such a way that corruption is really bad.
This means that if an elder or group of elders dislikes you then they can have you disfellowshipped and then once you are disfellowshipped from the organization the shunning begins.
I have a friend of mine who is an ex-JW because he started having doubts about their blood doctrine. He was sharing his doubts with some others on the internet who had similar doubts. His wife who is a very devout JW found the email that my friend sent, printed it out and gave it to the elders.
The elders formed a judicial committee to speak with my friend about his doubts. They really did not listen to his reasons for his doubts the focus was on being loyal to the organization. They told him that he had to give up his internet access to show that he was sorry for what he had done.
Even though he did that, the elders still disfellowshipped him and then his wife left him on the grounds of “spiritual endangerment”. The JW elders evidently encouraged her to leave him. His mother and father and sister do not speak to him to this day.
Once he lost his wife and every friend he ever knew (he was raised a JW) he had to be rushed to the hospital because he had an outbreak of the shingles (which can be brought on by being highly stressed out). His mother came to visit him. Her message was that Jehovah had stricken him with this illness so that he would return to the organization.
After this experience, he started building a new life without the JWs (good for him) and went for two years without seeing his mother. He even ran into his mother at a hardware store during this time but his mother either did not recognize him or refused to speak to him there.
In any case, these stories are real and there are many of them. We really need to pray for these people and help them when we can.