@ stan: I knew them both. I have asked the same questions and the answer is puzzling.
As a JW, to avoid too much mental conflict I took a lot of the Bible and JW teachings with a pinch of salt and I imagined that others did so as well, especially those in control.
As I was fading (already atheist and evolutionist) I went to a KH dedication led by Bevan Vigo, he was articulate and well dressed in an expensive and stylish tweed suit. A host of local councillors attended poor things! To have to listen to JWs ranting for an hour must have been torture for them but what interested me was Vigo's uncompromising denunciation of evolution. The subject was quite irrelevant to the dedication but it was his sense of being implacably faithful to a literal reading of the Bible which counted for him, even if he knew in his heart it was dodgy reasoning. The heavyweight JWs have to be seen and heard being utterly devout to the cause. Logic and evidence don't even make a showing.
It made me realise the possibility that there is a psychological charade taking place and a need to constantly top it up with JW rhetoric to keep the illusion going. My respect for Bevan Vigo plummeted.
Not long afterwards he suffered a breakdown and I did wonder if his submerged cognitive dissonance had asserted itself.