In scientific papers (where acronyms are common) this is definitely the rule.

IA (I agree).

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")

I don't know why people can't take 0.3 seconds to type "what does CTA stand for?" into their favorite search engine/LLM/text-message-to-a-friend. This is "Hacker" News, yes? What do hackers know how to do? Learn things, yes?

Oh, and I also don't know why this needs to come up on approximately every single post that has an abbreviation that someone doesn't know.

CTA is very obscure. As a mobile dev I refuse to call CTA as anything other than click or tap to action in which case it should be TPA. Also many folks (esp. PMs confuse CTAs with button clicks). Anyway, CTA in this context didn’t even ring a distant bell either for call or click and I am glad it didn’t.

I’ve worked with marketer types for over a decade and had them use the initialism “CTA” hundreds of times, understood it, and yet still in this comment I had no idea that they were referencing that term. If this was a UI diagram I’d have had no problem. This seems to me like a case where using an initialism in a different context than it usually appears confuses readers. It would kind of be like saying “I plan to GTM for a few things after work today.” You may recognize that as Go-To-Market if I said “the GTM team” at work, but it is strange outside that context. Outside a marketing or UI context I don’t think people usually initialize “CTA.”

It might not be obscure in an environment that lives on 'social activity', but I can assure you -- and I am saying this as a person, who survives daily barrages of acronyms, CTA is not common.

“Call to Action” is common. CTA instead of call to action is not common.

I've worked in software engineering on Internet things for decades and I have not once heard or seen this abbreviated before.

It's specific to marketing and it's a term I've only seen used when you are trying to sell a product. In my mind, CTA means "the button we are trying to make you click on by any means necessary because we make money when you click on it"

They could also write the comment in French, and by the same argument people should need to go out of their way to copy-paste that into google translate.

Thousands of people are going to read this thing. The writer could spare thousands of people spending tens of seconds (totaling days of human life), by simply spending less than a second spelling out the obscure term.