I don't know if they have relief valves in the hydraulic actuators or not. If the rudder activation system or the yaw dampeners malfunctions, it's perhaps possible that the rudder went hard over to full stop. By itself, that wouldn't cause an overstress. However, if the force caused by a hard-over rudder was combined by the force from the wake turbulence, it seems possible to me that the attach points were overstressed.

The point about repairing or beefing up one area causing overstresses in another area is well known in aviation. Many airplane homebuilders have fallen into this trap. A properly designed structure is designed to spread loads in a specific manner. Adding strength to one area can cause extra stress in another, sometimes to the point of structural failure.

At present, all I know is based on published accident reports. Flight 587 encountered wake turbulence from a 747. The vertical stabilizer came off, causing the pilots to lose control. The exact chain of events isn't clear. Like everyone else, I'm trying to understand what could cause that crash. Structural failure like that on an airliner is rare beyond belief. Something catastrophic happened on that plane. Depending on precisely what happened, there are possible ramifications that could affect a high percentage of all the airliners in the fleet.