It’s not a newly invented word. Google books shows both “initialism” and “acronym” to have been in use since the 1800s. Saying we shouldn’t have more specific words because many people don’t know their meaning doesn’t make a lot of sense to me.
> ... the first known published use of the term in English [is] from 1940
That published use is as follows [1]:
> Pee-gee-enn. It's an acronym [Ger. Akronym], that's what it is. That's what they call words made up of initials.
In other words, the very first recorded use we have of the word "acronym" is actually what some people insist on calling an initialism. I don't know who, afterwards, decided that "acronym" had to mean that it had to be pronouncable, or why, but I didn't vote for them.
> Saying we shouldn’t have more specific words because many people don’t know their meaning doesn’t make a lot of sense to me.
I didn't say it was because people didn't know their meaning; I said it was because as far as most people are concerned, they're the same thing. I know what "initialism" means, but I choose not to use it, because as far as I'm concerned "NASA" and "FBI" are fundamentally the same thing. It's a waste of brain cells to figure out when to say "acronym" vs "initialism".
As an example where I think such a distinction is important, I do consistently write "MiB" when I'm talking about 2^20 bits. I only saw it the first time maybe 10 years ago, but it immediately seemed to be to be both practical and useful to make that distinction.
On the other hand, I never correct or ask clarification of people who use "MB", unless the difference becomes important. (Nor do I say "mebibyte", which is the proposed pronunciation of "MiB", because it's impossible to pronounce fluently.)
