Is there a clear leader/facilitator in that discussion class? Someone who keeps the discussion "on track" and prevents it from wandering from the chosen topic?
That would be different from the spontaneous, unstructured conversations the article is talking about.
Now, it does break down somewhat when the core discussion is over or if someone is a bit disruptive (which has happened recently).
As a sibling comment to yours wrote, it DOES help that the topic is understood among everyone present, there is a clear intent to the gathering, and everyone has approximately the same motives.
That would be different from the spontaneous, unstructured conversations the article is talking about.