I don't disagree that some of these bootcamps teach some knowledge and lead to jobs afterwards. But what you're really paying for is networking. Even junior development work requires a fairly robust set of knowledge, that isn't going to be grokked within 6 weeks or even 3 months (unless they were already familiar with computing/unix etc). That model only works for companies that are willing to onboard -very- green junior developers and mentor them long-term.

You can accomplish the same thing by following courses/books online, making a handful of projects on github to show interviewers, and networking at conferences/meetups. That's how I landed my first part-time job with programming, and then my first full-time job.