We "left," but we were never really there in the first place. Since then, I have met so many people whose lives have been touched (or torched) by the influence of the WTS.
You asked a great question, and I do agree that people are underestimating the power of the Internet in reaching people.
Many people will pass right by, or right through, the organization and not give it much thought afterward. Others have their entire social and support network demolished, leaving them so devastated and alone, having "nowhere else to go."
I honestly didn't take any action for a couple years after changing my mind about the JW's. It was not until my tree got shaken more violently, that I realized I should actually take another look (with open eyes).
I am so grateful to find this forum, and all the people here who are willing to share their experiences. I am learning a lot.