Yeah the problem is most JWs only think as a last resort. Look at HLS. When a JW has to use their brain to pick medical treatment they have no problem running ahead of the watchtower. It is almost as if they decide to give the watchtower the benefit of the doubt that the bible only talks of whole blood. Then take disfellowshipping many JWs are traditional. Others in the privacy of the office or home ignore the watchtower.
The problem I think like any good story suspension of disbeif is key to religion. The watchtower exploits this. The heartbreak comes when you realize that the things you were told to suspend your disbelief existed for that sole purpose a simple plot device .