Some think of a cult as being a dangerous religious sect with a human leader. Jehovah’s Witnesses do not look to any human as their leader. Rather, we adhere to the standard that Jesus set for his followers when he stated: “Your Leader is one, the Christ.”
This is what the JWs claim. In reality they obey their human leaders. For example if you took Haemoglobin in 1980s you would be disfellowshipped. Now you are allowed to do it. What has changed? Bible is the same, Jesus is the same... the only thing different is the GB pronounced their fatwa and allowed you to take Hgb. Hence to take Hgb is no longer 'prohibited by the Bible'. You can think about organ transplant ban in 1970s in the same way.
JWs obey their religious human leaders. If the GB says tomorrow you can take plasma transfusion too, all witness apologists will stop to argue the ban on blood plasma is 'biblical'.