But there are planes which do not have vertical surfaces at all. The classic Etrich Taube (which has tail with tailplane and elevator, but neither fin nor rudder - turns are made solely by wingtip warping/aileron), Northrop B-2 (no tail at all!)...
None of which have any relation nor bearing upon a swept wing jet transport category airplane, as pertains to the question at hand. Also the reason the answer was given "conventionally configured airplanes."
Issues regarding engine-out operations are likewise irrelevant, as flight 587 didn't have an engine problem. It had a missing major flying surface problem.
Surely what really brought the aircraft down (before directional stability played any part) was the CG upset.
Surely not. Center of gravity was the least of their worries, as they lost directional control due to a missing vertical stabilizer.