One panelist quoted and inverted Foster's definitions of a story and a plot. Reversing the king and queen was one thing, but he described "The queen died and then the king died" as a plot whereas "The queen died, and then the king died of grief." Another panelist took off with it as the matter of the first being a mere chronology and they explicate how a mere sequence of events is not a plot or a story.
The need to make things clear. I asked about why they were talking about "the reader" when some readers need more than others and sometimes you have to aim it as one rather than another. Which inspired most of them to talk about the need for feedback, and how some writers need to be told to be more subtle, and others to be more clear.
It can be dangerous, twisting a plot. Especially the nearer the end you get, and most especially at the climax. Events should be surprising but inevitable in hind-sight.
You need high stakes, and some panelist could not stand some works for the lowness of the stakes. And the stakes have to build, which is one reason why twists are a peril.
Why doesn't Frodo just chuck the ring away and go home? The need to give the characters a reason to stick to the task.