Personally I doubt that about many. No one is going to admit that they stopped believing in God because of the acts of an organization
I don't think this is a fair conclusion to jump to, CA. First of all, because it completely invalidates, and nearly calls a person a liar. It is an assumption, and a person telling another person what their true motivation is. Nobody here is qualified to do such a thing.
Cofty turned Baptist (I think) after leaving JW's, but I was involved in many religions before becoming a JW. In fact, from that list in the OP, I've been most of them at some point.
Also, I was not upset with the organization at all, when I concluded there was no evidence for a god. I didn't even know I was coming to such a conclusion until I finally did. Then it felt like a lightbulb moment, but in retrospect, I realized it was something I had been working out for quite some time. I was not upset with the organization until much later, when I saw the damage they were doing. I went from feeling like they were just misguided, to believing they were purposely being misled. But that played no role in my shedding god belief.
I think for a JW to free themself, it takes a huge amount of critical thinking. It takes real exposure and vulnerability. It's not the same as going from Baptist to Catholic, or Methodist to 'spiritual', but an honest and brutal reexamination of the ideas held dear. ALL of them, not just the religious ones. Once critical thinking has kicked in to that level, then no belief is safe. It keeps going until the very existence of god is considered. That, in my opinion, is what leads exJW's to atheism. They keep up the critical thinking until they get to the core.
For me, and the many religions and spiritual minds I've had, the only common denominator was a god. It was time to study out that god, and I didn't find him/her.