Customers are being trained to repeatedly scan barcodes to check the price on Amazon. Something that, rather conveniently, they can then do in every other shop they visit.
It's a joke on using a Captcha to detect a human user - this is the opposite, a way of only allowing robots to access information, and to keep away humans.
"...Labbé, who has built a website where users can test whether papers have been created using SCIgen..."
It's so lucky that he's built a tool to check whether a document is "computer-generated nonsense". God forbid that the publishers have to actually read the papers to check.
I just registered to reply to your post. I am a designer with a couple of decades experience. There are of course design 'rules' but there is just as much intuition and familiarity.
If I can make an analogy, it may help explain the process of choosing typefaces for a project. I really hope this doesn't come across as pretentious nonsense, as anyone can learn about type, but it really is mainly down to experience and a desire to learn:
So let's say your job is to choose the songs that appear on film soundtracks. You need to be aware of the mood, era and style of the film, and choose compositions to match. Now due to the nature of your job, you will be more aware than the average person of music around you - you are constantly conscious of it around you in your day to day life, as well as researching the history of specific songs and tunes, in your own time, purely for pleasure.
So you'll have built up a mental database of knowledge. For a specific film you could include a popular song that many people are aware of, or you could choose something more obscure, but more appropriate. You might choose a selection of songs by the same artist, or tunes from the same record label, or all songs played in the same key. Simply having more knowledge means you have these options.
There could be a set of rules written for choosing music - 'In a tense scene, use this type of tune', and that would be fine, but it really is one of those things where experience over time, and an enthusiasm, is more valuable than just going by the book.
Bringing it back to type, it's a case of knowing about the moods generated by each typeface. From day to day I am constantly aware of the typefaces used on shop signs, TV and film credits, newspapers and posters; but I also know what fonts would have been used in the same circumstances in 1979, or 1962, or 1890 (although not so much on TV then).
So I've probably not done anything at all to dispel your idea of 'priests of a mysterious religion', but I'd personally compare it more to a hobby or pastime, which, if you're lucky, you can get paid to do.