I don't think that is necessarily the case. If you use certain words all the time, shortening them makes sense. They might just forget which abbreviations are and aren't common knowledge. You wouldn't get mad if people use PC, CPU, ATM and RAM, right? Even SSD would be fine on HN, but it probably wouldn't be fine outside HN. (neither would using "HN")

> Even SSD would be fine on HN, but it probably wouldn't be fine outside HN.

The set of people who know the term "solid state drive" is likely a strict subset of the people (mostly tech enthusiasts of some shape) who know "SSD". Same for "USB" and many other terms that have entered the mainstream primarily as an abbreviation.

So the question is not whether to use an abbreviation or spell out the full term as a matter of principle; the question is whether it's the abbreviation or the full term that's more commonly known. I'd argue that way fewer people recognize "CTA" than know the term "call to action". I personally have done some front-end development, and didn't know the abbreviation either.

Without context ATM could be Asynchronous Transfer Mode or automated teller machine.