Why do so many people insist on using incomprehensible, obscure, ambiguous acronyms all the time? [closed]

Why did you write "ambiguous" instead of "with several possible meanings and no way to know which one is meant"? You didn't write it in order to feel smart or because you wanted to waste my time, did you? You wrote it because that's the word that came to mind and you thought people would understand it.

The same goes for acronyms. The term "PPE" is pretty common (in some groups, at least); it comes to mind naturally and most people in the intended audience are going to understand it right away. So of course people are going to use that term.

It's not hard to find out what "PPE" means using, say, Wiktionary (3 definitions, and the first one is the intended meaning here) or a Google search (9 results on the first page for me, and all of them are the intended meaning here).

(If you're in the habit of using Wikipedia to try to find out what words and acronyms mean, stop doing that and use a dictionary instead. If you're trying to figure out what the word "amazing" means and you look it up on Wikipedia, you'll be disappointed.)

People use jargon to establish themselves as members of their “in-group”. It’s annoying in many ways, sometimes even to members of the in-group itself.

This article by Joel Klettke gives a slightly different perspective on its use, and the accompanying video is quite funny.

https://businesscasualcopywriting.com/why-people-who-hate-jargon-are-wrong/

Joel points out that sometimes the purpose of jargon is to filter out readers for whom the text has no relevance.