HI SBF!
I can't quite agree with you that you compare the slaves of the Watchtower society to christians in general.
Christians in general are not shunned by their relatives if they choose to leave their church, but the JWs are trapped and chained like literal slaves. If they break the chain gang they themselves lose everything and their relatives also suffer as they have to shun their loved ones.
Christians and Jehovah's Witnesses are two completely different 'things'. You cannot compare them in the same way. So the fact that christianity has declined and yet JWs haven't as much as expected, really isn't here nor there.