Note the thick chord of the Elevator vs the Stabilizer. My guess they were looking for greater strength via the thickness as well as maybe getting the airflow not to separate and as stay laminar as it went over the gap, by causing it to accelerate. More effective elevator for a given span is my guess. I have seen this technique used on one Acrobatic Aircraft's Ailerons...
Thanks for the photo post. The diagonal angle of the stress marks suggests that the rear fuselage sheared with an upward force by the wing, and downward by the tail. Which is consistent with loss of a trim tab operation that normally provides upward force at the tail to counteract excessive lift at speed, and when lost would generate major downforce.
I’m not an aviation expert, but I did earn an engineering degree once upon a time.
Maybe a simpler way of looking at it is that this is what happens when positive Gs exceed the airframe’s capability, but the wings are strong enough not to fall off.