Were it not for new children born into the cult, or men/women dragged into it by their girl/boy friends, the JWs would likely have no growth at all. The field service work is nothing more than the society doing what the society does best: demonstrate to the individual that they are in control of your life.
You are not allowed to have a hobby that will take time away from your field service on Saturday or Sunday. Not allowed. These people are smart enough to know that field service is a fraud and totally ineffective for bringing in new ones. But it works perfectly for its intended purpose - to demonstrate to you that you are not in control, do not own, your own time - they do.
New poster for Kingdom Halls:
All that is not mandatory is forbidden.