JW's are never told why their friends leave. A simple 15 second public announcement is made that so and so 'is no longer a Jehovah's Witness'. JW's are taught to mind their own business, not to gossip, and not to question things they don't understand. Jehovah is mysterious. Only the leadership is entitled to know why someone got disfellowshipped.
Thus JW's assume the worst. Disfellowshipped JW's must have done something terribly evil like Paul described in 1 Cor 5:13; JW's believe the Watchtower protects them. There must be good reasons why their friends were thrown into the dumpster. JW's believe it's not necessary to know private details about other JW's. The job of snooping into the private lives of others and judging who God doesn't love is the responsibility of Elders.
JW's believe the Watchtower is protecting Witnesses from 'Satan's world' and that's why information is censored. JW's believe information is censored for the same reason loving parents would censor violence, bad language, and pornography from their children. However the Witnesses have been deceived. Censorship does not protect JW's. It protects the WT.
If Watchtower teachings were built on a solid foundation, there would be no reason for censorship. JW's could read anything without fear that their faith would be shaken. Matthew 7:24-27
If you read the secret rule book for Elders, you'll discover that anyone can get disfellowshipped if the Watchtower thinks a JW might disclose it's secrets to fellow believers.
The Watchtower warns JW's they must not visit websites such as this one because the world outside the Watchtower thinks like Satan. If JW's consider what former JW's have to say, the Watchtower says they'll catch 'mental disease' and die. [WT, July 15, 2011, Article: "Will You Pay Attention to Jehovah's Clear Warnings?", p 11-16; par 5-13]
As funny as it sounds it's true. The Watchtower teaches that former JW's are 'mentally diseased' and listening to the viewpoints of people outside the organization can kill them like a real contagious disease.
The Watchtower knows the truth. If JW's research the Watchtower and leave, they will be treated as if they are dead and given the same respect as used disposable diapers. They will be treated like trash. They will lose their families, friends, religion, and 'life' as a JW. They will be shunned forever.
That's how the Watchtower keeps their secrets safe.