Checking to see if it's 1999...
I'm an IT guy, not a developer, so my experience lies with the "MCSE Bootcamps" that sprung up towards the top of the First Dotcom Bubble. I went after doing the MCSE myself because a consultancy I was working for at the time paid for it. If you were there for an upgrade like I was and knew what you were doing, it was a good way to cram for the stupid tests in a very short time. However, these bootcamps also enrolled a lot of complete newbies ("career changers") who were truck drivers and similar in a previous life. This is where we got the term "paper MCSE" from - the bootcamp taught exactly what you needed to know for the exam, and very little else.
I can only assume that these coder schools are very similar. What do you know when you come out? Maybe one or two JavaScript frameworks and a couple of back-end tricks? It makes sense now, when you have web startups grabbing for all the starry-eyed "talent" they can get and working them 100 hours a week. But once the bubble pops, or even just slowly deflates, there's just not going to be a need for millions of AngularJS junior developers.