I studied rhetoric and technical communication for some time, and know quite well the usefulness of field-specific terminology for initiated readers. This, however, is not a comparitive-historical linguistics symposium and, as a multidisciplinary forum, I find no reason we should not to expect commentators to write to their actual audience.
Down-vote all you like, it doesn't change the fact that jargonistic writing for general audiences is rarely necessary and most often laziness.
I recommend you avoid throwing around accusations of laziness: if you're genuinely not aware that PIE stands for Proto-Indo-European language, http://en.wikipedia.org/wiki/PIE acts as a perfectly good source.
I've assistant edited academic journals and spent years as a copywriter/editor at a consulting firm that worked in many specialized industries. That accusation was leveled with purpose and from experience.
This is not only about the acronym above, though PIE does have many meanings[1]. That an acronym has a specific meaning to a specific group is why it is jargon. That it is "not a novel concept in the field" further reinforces that and is justification for writing it out, given the audience. It's really that simple.
The primary effect of acronyms on a non-indoctrinated audience is to reduce the writing's accessibility.
Simply, this is not a linguistics conference nor journal forum, and it is inappropriate to assume the folks here will know field specific acronyms.
Does it make any difference that it is spelt in full in the linked question?
> From the top of my head, Danish "de" (practically never used), German "Sie", Chinese "您", French "vous", Spanish "usted" are a formal way of addressing someone, especially if one isn't familiar with the addressee. Did English ever have this? It sounds as though Proto-Indo-European might have had this (based on my 4 examples), but perhaps someone can enlighten me?
You think the use of PIE is bad, just wait until they bust out the ASCII IPA.
(I am thick as 2 short planks but I've heard of PIE. HN should be a place where people like me need to work hard to keep up.)