At lower altitudes, where Vmo is limiting with a jet aeroplane, to then exceed Vmo by some margin exposes the aeroplane to increased dynamic pressures, with resultant difficulties, including the possibility of increased control surface flutter.
Even with turbopropeller and large piston designs, this was possible.
For example.
The DC-6B experienced elevator flutter during flight test when the maximum authorized indicated airspeed was reached or just slightly exceeded.
A fix involved additional hinges installed at the outer ends of each elevator.
In my considered opinion, if a pilot should decide, on their own and for no good reason, to exceed Vmo/Mmo deliberately, would/should be grounds for license suspension....if not ready for the rubber room.
