Boot camps are no silver bullet. Like any kind of education, more is better, and the quality of the student is a factor. I will admit that while I got a great job, but there are fundamental CS concepts I'm still playing catchup with. Not sure if I would really be all the more effective as a developer if I did have a traditional degree, and maybe I would, but I can provide for my family and have no regrets.
All said, I think you might be right about some selection bias.