How about another perspective?
Maybe it's not so much about wasting the JW's time, as much as it is the fear the potential recruit (AKA: Study) will actually be SMART, and decide to fact-cheque and research what the JW's are telling them, OUTSIDE of JW-approved sources?
We're hearing more and more about this on the forums: JW's, even "Lifers" that have been woken up because their Study decided to look outside of the JW-approved liter-a-trash and go onto Google. Then, the appalled Study shares the info with the JW and demands some answers. Well, the JW of course has to research this matter for themselves in order to clear it up. Imagine the JW's surprise when shit don't add up!! Sometimes, the "awoken" JW then goes and starts telling close JW friends, more liberal Elder types, etc.
I see this as a control tactic by the Governing Body to keep JW's moving. The more time the JW spends answering a thinking-person's questions, the more likely they are to fall upon the multitude of free information on Google.
Remember, pretty much everything the WT HQ puts out now is not pro-active, but RE-active. As-in, they are reacting to what they are being told by the CO's reporting back to HQ from the field.