The WTBS has two fundamental problems in this.
1) they have no standards for hermeneutics and exegesis, that is the methodology of used to understand a text and the resulting interpretations. These would include careful analysis of who wrote a particular text, who he was directing his comments to, as well as close critical textual examination of a text. The WTBS runs into trouble because it doesn't apply any of this to any text, everything is taken as literally true and subject to their understanding of what that means. Since they have no standard method for explaining a verse, they can just shoot from the hip all the time.
2) A classic method of control is to constantly move the goals, purposes etc of whoever you're trying to manipulate. I've worked for a couple of control-freak bosses and it is very much like have the GB as your boss. You have to do it exactly right, or you'll get in trouble, but what is "exactly right" changes constantly. You're lucky if you get to find out in advance what that is.
edited to add: I spent some years as a member of a "mainstream" church. That church and a majority of other protestant denominations all agree on what they consider major doctrines: salvation by faith, the divinity of Jesus, Baptism, regular communion etc. All of minor points are left to the individual to decide for himself, and are not considered major points for argument. Most of the differences between churches involve worship style and governance, not doctrine.
The WTBS regards individual thinking as intolerable.