But if you still adhere to the so-called principles, don’t you by extension still fall under the power of the GB? These rules were invented by men, they have no grounds in reality, obviously you rejected the men and some of the rules, so you must reject everything that is connected to that. This is interesting, because you adhere to a religion as a snapshot in time, eventually you will fall outside the acceptable (outside the Overton window so to speak) as the men make up and adjust more rules. So the question is which snapshot do you accept and if so, why?
If you reject the principle that the current GB is appointed by God (which you must, since if you accept they are appointed by God and reject them, that is worse than an unbeliever) then you must reject the principles that go along with that.
To go with your analogy, you find out the doctor has been giving you advice on diet that benefits his family’s food and drugs company and is actually providing you with toxic substances instead. You decided to reject that doctor, but still keep shopping at his company. If you think the Bible or even JW at some point had good advice, or a kernel of truth, you must investigate fully what is and what isn’t introduced by the GB for the sake of their own benefit.