The witlesses do practice discrediting of all other sources except the ones they specifically permit, usually themselves. Anyone that reads the Bible in fully integrated fashion hasn't been through THEIR program and thus will not be upheld as knowing about the Bible.
I notice this theme in various types of cults. The medical cult (which is run by the big drug companies and forces all those practicing medicine to go through) is no different. They do not respect anything unless it appears in journals that have been reviewed by the drug companies. Like the Washtowel religion, material that comes from independent sources (which is often far superior) is denigraded as "not having been through our system" and "not peer reviewed" (or "not coming through God's channel"). Those who realize that the cult is bogus and practice the truth (against the cult) are looked down on by the cult, often shunned by the Establishment. Often, they have their careers ruined when they go against the cult--very similar to the Jehovah's Witless cult.
I also notice that they are similar in attitude toward "worldly people". I have a dentist that consistently urges me to "be very careful about what Internet sites I visit" (sounds like the Washtowel cult). This person will not get past the use of fluoride (sounds like the Washtowel not getting past their own doctrine), despite that calcium and phosphate are the two major building blocks (like the hounders that will not accept the Bible instead of a washtowel rag as proof of a bad doctrine). And, they insist that I not use baking soda on my teeth despite that calcium hydroxy-phosphate is the dominant form of mineral in teeth (sounds like not using your Bible as the primary source of information about the Bible). They claim that, since I did not go through the ADA approved course (and neither did most of the people writing up those articles--they are mere chemists that study minerals like that for a living), they are invalid (like the Washtowel claiming that, without their own material, you cannot understand the Bible).
Business cults are similar. I looked into a MLM called Herbalife, and they try to instruct you as to what to say about their products. I noticed the following problems with their products: The ingredients were very questionable (acesulfame K, aspartame, sodium caseinate). They were no better than cheaper products you find in drug and department stores. They had no net weight in the catalogs--and I checked (the law says that you have to indicate how much product you get for that price). And, they asked for sales tax in my home state (I'm no business expert, but I know that you charge the tax in the state the product is delivered to and not the state where the product is sold from.) The difference is that the rules are less rigorously enforced, with the primary threat being that you will fail in your business.
And yes, I will call the Jehovah's Witlesses a cult. They are every bit as reluctant to allow independent sources as credible information as the medical system and other religious cults, and even worse than most business cults. They do occupy all your time (like the medical system and most business cults). You are always researching through Establishment sources, never allowed to do your own. And, they waste huge amounts of time trying to recruit new people.