People quite often find it prohibitively hard to talk merely because different groups have gotten into the habit of talking differently, even though their concepts could be translated without great difficulty. And members of these groups often go out of their way to signal group loyalty by choosing to talk differently than outsiders.
He refers to what seems like a fascinating article, which is behind a paywall. If I could put this in Hansonian terms, I would say that language is not about clear communication. It is about signaling tribal identity. Often, it is important for the signals not to be easily picked up by another tribe. And, yes, of course, this applies to jargon used in various academic disciplines.
Incidentally, one of the ways I describe the three-axis model is that progressives, conservatives, and libertarians speak different languages. Each responds to disagreement by, in effect, shouting louder in a language that the other party does not understand.
UPDATE: thanks to a reader, a quote from the article
we have acquired a suite of traits that help our own particular group to outcompete the others. Two traits that stand out are “groupishness” — affiliating with people with whom you share a distinct identity — and xenophobia, demonising those outside your group and holding parochial views towards them. In this context, languages act as powerful social anchors of our tribal identity.How we speak is a continual auditory reminder of who we are and, equally as important, who we are not. Anyone who can speak your particular dialect is a walking, talking advertisement for the values and cultural history you share. What’s more, where different groups live in close proximity, distinct languages are an effective way to prevent eavesdropping or the loss of important information to a competitor.
The author, Mark Pagel, has a book called Wired for Culture, which I will want to look into. On the Amazon page for the book, Herbert Gintis has a fascinating review.