I think jcjeant has a strong point here. With FBW, training "can be" shortened, it inspires confidence, sometimes without the mode to back it up, (BOAC), It is seductive in that "stable flight" is actually cheaper than manual (in the long run), etc.
For me coffin corner is all vectors of flight are maxed, and cannot be stretched, or modified, without upset. Too fast? Pull up. Can't, Stall. Too slow? push yoke. Can't, overspeed. Want to turn? Sorry, drop a wing and roll into a spiral. Etc.
The very best format for avoiding problems with CC is either one, FBW, or Conventional. The edge? Neither one. Where a pilot is not as precise as Otto, neither is Otto aware of the potential disaster, just as A Prot can be compromised by another "protection". "Don't touch" is a human skill, evidently not so much with Otto, except when it gives up on the a/p, and runs for cover. (447)
The word "Protection" I find offensive. Can we lobby for a refit of nomenclature?