Because the truth is that the technical work is not the barrier, but rather the grit to grind through the hundreds of little problems that you'll encounter on the way to getting a working piece of code. So "do a coding bootcamp" functions as a rapid weeding process where someone can find out quickly if they're up to the career or not. Then if they're not, they didn't waste a ton of time finding out that it doesn't work out for them, and if they are, then the bootcamp will provide further vectors to progress.
Besides "get a CS degree", what are the other alternatives? Telling people to learn how to program themselves isn't very successful; if they were the kind of person who'd do that, they'd have already done it; it's not like they were just waiting for someone to tell them to do it.
Because it's a way into tech for non-tech people? This wasn't, as far as I understood, a general suggestion for all English majors, but for those that allegedly used to be able to simply start in tech jobs 20 years ago. Now they may need a bit of prior knowledge, which boot camps can help with.
Because the barrier to entry is still quite low. While maybe not "Anyone who could spell HTML could get a job" low, as said in another comment here, it's still so low that I'd wager a decently clever person with a good 3 month bootcamp can get a _entry-level_ job.
That's a fallacious argument though, because at the lower end tech jobs pay more than other careers but result in you being exploited by corporations looking to drive wages down.
When I graduated, there were companies offering me 30-40k a year in cities like Seattle. I have friends that could tell you the same story, some who took the opportunity because of the entry level market being saturated.
Bootcamp graduates are often placed in incredibly exploitative contracting environments (often in companies that also underpay, abuse and threaten H1Bs) which are farmed out to larger companies looking to get work done cheap. Though this has just been my personal experience and that of my friends. They leverage desperation.
It's really become rather saturated at the entry level.
It's a market for lemons situations, where there may be a lot of opening, but there's tons of unqualified candidates.
I never understood this either, it's not practical advice for most people. You might as well say "become a plumber", "do electrician school", or even "go be a doctor".
There are a variety of high demand and well paying jobs, but not everyone is interested in them, or even cut out for them.