John Lear maintains that VMO is an absolute aerodynamic limit on the airframe above which flutter would prevent novice pilots performing the manouveres.
Thus proving quite conclusively that engineering skill is not an inherited trait, because that statement is complete and utter garbage.
VMO (and MMO) are exceeded in flight test on every single aircraft. Even VDF/MDF (or VNE) are not ABSOLUTE limits - they are the limits beyond which it is no longer
known to be safe - not the limits where it is
known to be dangerous. Margins between VMO and VDF are typically of the order of 50-75 kts (just like the old VMO/VNE splits); margins between MMO and MDF are typically of the order of 0.05M-0.07M.
In fact, its a requirement that VDF/MDF be DEMONSTRATED in basic certification.