A specialist discussing a complex topic uses that as shorthand based on shared context. Nothing would ever get done if every conversation required starting from "first principles" whether inside or outside academia.

What's missing in your claim is evidence that people in academia often mischaracterize this style of discussion from accumulated knowledge and shared context as "thinking from first principles". I don't see any plausible rationale for why they would.

Otherwise, using their typical mode of interaction from outside observations to infer they misunderstand first principles is not a standard anyone doing specialized work inside or outside academia would ever be able to meet.

The private sector would grind to a halt if discussing a specific IEEE 802.11 protocol implementation with a fellow SME required a lengthy preamble of networking first principles before answering in order to be epistemologically sound.

Similarly, using a conversation overheard at a conference to infer the experts lack first principles thinking would not be reasonable just because they appealed to IEEE documents instead of rearticulating the underlying decisions made by the standards committee.

Your reasoning that first-principles results in inefficient communication is false. It is a common misunderstanding.

You can always breakdown one layer on demand. And you only need to drop down as far as the other party insists.

My example was about striking up direct conversation with someone and not overhearing.

If someone pointed to IEEE protocol and I asked "but X, so why?" and if the answer is still IEEE protocol again, then the person does not have "first principles".

That is the test. It exposes the shorthand user from the legit first-principles capable user.