The thing about programs like HackReactor is that they are methods for the big tech companies to gain access to a kind of super-technician programmer. There is a huge problem in finding and hiring competent programmers. I've seen it myself. There is typically no good way for a company to really know if a given candidate is really a capable programmer or not. There's also a huge downside to hiring someone who then turns out to be not very good. In fact people speak of "negative productivity" and it's a real phenomenon.
In order to combat this issue, and to take advantage of the folks who want to want to try to catch the brass ring (of a well-paying career in the software industry), they've come up with this idea of a programming "boot camp". They basically get people to pay for their own probationary term and then filter them for those people who are likely to do well as junior "technician" developers. The students are, in effect, subsidizing the hiring process.
In this case, the reason why HackReactor can boast of such high rates of their "post-grad" hiring is that they are very very careful up front about who they let in. That "interview" process they talk about is designed to vet people based on how well they can pick up tech and software stuff. It's openly acknowledged that there are people who "just get" computers and people who really struggle. HackReactor are very careful about only accepting people who are already strongly biased toward being able to "hack it" (no pun intended) and then teaching exactly what they want them to know, so that they come out of the program already proven (to some degree) and trained. Of course they get hired. :-) That's what the program is really for: finding and supplying a work force.
I would recommend attempting the "interview" because you will learn a lot just from that, however, unless you are just wanting a job as a mid-level software technician the actual program would probably be a waste of your time and effort.
As a counter-example you could learn everything they are teaching from a community resource such as the Mozilla Developer Network.