the most important lessons from this accident aren't so much about how a manoeuvre was flown, they are more to do with the safety of public when a planned display goes wrong.
Yes but... those two themes are not mutually exclusive. Public safely, particularly non participants, must be of the highest importance. But, what was there "new" to this demonstration in terms of risk and hazard, which could not be anticipated based upon an understanding of the requirements, and previous events?
It is well known that a loop or a roll along the show line can go wrong, or an aircraft can be stalled in a tight turn. The resulting trajectory of the uncontrolled aircraft is not hard to anticipate....