The D2D work is absolutely fruitless! I believe a poster on another thread mentioned that he had just one person baptized at his CA. If that is the case, and believe me it is not much different in my neck of the woods, then the preaching work isn't worth the effort. Other churches are growing much more rapidly than the JW's and they don't preach at all! In fact, if the ORG was SOOO concerned about preaching to the masses, they would have embraced TV, Radio, and the Internet long ago. Do what works people!
No, the purpose for the D2D is a little more insidious in my estimation. In order to fully understand it, one must return to the days when chalkboards were used at every KH. Every month the Bible Study servant would have the names of ALL the publishers along with the hours and placements and this would be displayed to the Congregation. It had a twofold purpose: #1-To openly praise those that served as the ideal JW and #2-To openly berate those that were not. It was a testament to your "faith" and "commitment" to the ORG.
In time, this particular aspect of the ministry was done away with. It was unloving and led to considerable issues with weaker publishers and, I imagine, the inevitable "padding" of time. What hasn't changed, however, is the same "praise" and "berate" philosophy. The D2D is a measuring stick. It is a barometer. Where Paul said a person is saved by grace (mercy) and not by works, the ORG says, Faith without works is dead.
No, the D2D is an act of humiliation. It serves to "temper" the ego and self-respect that all of us have. That is why the ORG states SOOO emphatically that the "apostates" are the first to question the need to preach. Funny, I have never heard an apostate once question the act of "preaching" only the message preached.
Just a thought,
SOP