This seems fishy, but nobody has mentioned it yet:
The dominant language of the early Church was Greek, and in Greek the phrase “Jesus Christ, Son of God, Savior” produced the acronym ICHTHYS, the Greek word for fish. A Christian poem of the second century spells the word with the first letters of each line.
Acronyms that produce recognizable words seems to be a common idea.
Well the first three letters of the second word, but who’s counting.
I don’t know about anyone else, but I have no problem considering constructions with more than one letter from each word to be an acronym.
Insurance Company of North America, called INA, was founded in 1792, and started out offering “fire insurance” to people in Philadelphia (apparently they were novel in insuring the contents of a building in addition to the structure itself).
It’s not entirely clear to me if they were always referred to as INA, but it’s what the company is usually called.
Yes, of course. But people rarely if ever do that anymore. It’s certainly sketchy on the Dope. I wonder when in initialism history we stopped spelling things out when first using initials? I think it was a 21st century thing where it exploded with the use of smart phones.
And at some point people started thinking, “Gee, if I know that acronym, everybody else must!”
The Dutch East India Company or Verenigde Oostindische Compagnie was the world’s first joint stock company. It was universally known as the VOC, and those initials were plastered over a lot of their stuff. The wikipedia article cites a credible assessment that the classic VOC logo was probably the first globally recognised corporate logo.
The Peabody Essex Museum in Salem, MA has a collection of Dutch East India stuff, all with the VOC logo on it. (Salem had an extensive trade with Asia, which they’d rather you remember about the city, rather than that unfortunate business with the witches. Hence the VOC stuff.)
Because there are some acronyms that not “everybody else” but most people in the writer’s audience know. I doubt people go around writing Federal Bureau of Investigation or National Association for the Advancement of Colored People when the FBI or NAACP first come up in an article, post, email, etc.
Where I work, there’s a strict “use the words the first time” policy in our writing (and our job is churning out writing!) but everybody 
looks the other way when Deoxyribonucleic Acid comes up.
There’s also royal ciphers - those ER (and now, CR) common on things like British mail boxes etc.
Generally they are clever arrangement or intertwining of initials, but the point is they use the first letters, of say, James Rex (JR) for James II in the late 1600’s, or George Rex (GR) for George I in the early 1700’s. The old-timey folks were not unaware of lead letters standing for whole words.