I've had a similar experience at my job and I think it's actually both things.
On one side you have people that managed to claw their way through the boot camp but didn't actually pick up any of the skills; they memorized enough to get through instead of actually learning stuff. On the other side, you have people that did learn but aren't confident in their skills and so flub the interview when their confidence gives out.
I've watched the latter happen on more than one occasion and I really wish I knew how to handle it as an interviewer.
On one side you have people that managed to claw their way through the boot camp but didn't actually pick up any of the skills; they memorized enough to get through instead of actually learning stuff. On the other side, you have people that did learn but aren't confident in their skills and so flub the interview when their confidence gives out.
I've watched the latter happen on more than one occasion and I really wish I knew how to handle it as an interviewer.