I attended a coding bootcamp recently. It was fun, but it turned out not to be a good use of resources. I suppose I'll need to explain my situation there.
I had been coding in relative obscurity and isolation for some years, and (1 I wanted to pick up Ruby, which I'd read 5-7 books about but not really done much with, and (2 I had no social connections and no idea of my relative skill level. I'm still not entirely clear on that score but my teachers were pretty insistent that I knew more than them about the course material; I ended up dropping the program.
Either way, I spent a lot of time getting to know people there, of widely disparate backgrounds, who were mostly learning to code for the first time. After several months in company, I could probably pick out one or two out of the cohorts who I would feel confident in saying, "this person is going to be a 'Real Programmer' some day". And to me the difference was not necessarily about native ability; I think that there are quite a lot of people, perhaps even the majority, who can learn to code at a high level eventually. However, it also became clear that people had very different styles and rates of learning, and they had very different goals and reasons for being there.
I think it's probably possible to master all aspects of programming in a decade or two. I'm pretty sure that mastering all aspects of programming isn't even the goal of most programmers, and most people will never get there. That's not a bad thing in any sense; it's possible to have an excellent career as a programmer and never e.g. write a compiler from scratch.
So with the overall idea that people are on different paths, starting from different points, and progressing at different rates, I would probably say that [1] anyone who is three years out of a coding bootcamp with no prior coding experience should not be in a senior dev position, and [2] you may or may not be doing the bootcamp grads a disservice.
I was immensely impressed by the rate at which people were able to go from zero programming knowledge to being able to solve problems in whichever framework happened to be thrown at them in a given week. What is taught in bootcamps is not how to be a programmer -- no months-long course of study could do that -- but how to learn how to learn programming. The bootcamp grad is not a finished product, they're a work in progress. That may or may not be useful to you, but I would argue the merits of bootcamp grads as junior developers over the majority of CS graduates -- at least if this post were not already too long. Of course, if your position is simply that you do not hire junior developers, then that's a separate issue.
All said and done, I'd try to keep an open mind about bootcamp grads. They're not going to be well-rounded developers, but completing a bootcamp tends to mean learning a lot of different skills very quickly. I don't think I saw anyone at my school of which I thought, "this person really ought not to be here," or "they're never going to make it in the real world". If you saw a lot of bootcamp grads and passed on all of them, I'd say odds are you missed out on at least a few pretty talented people.