I agree with you about the stress at the point where the fork leaves the frame at the top ofthe headset. Don't you also have a point of stress at the bottom of the stem? I would think with no spacers, these two points are pretty much together. By having some spacers, don't you have a length of steerer tube between these two points that spreads the flex over a greater area making it less likely to snap? Again, I'm not saying this is the case...I'm just asking if this makes sense or not.
Greg.
Greg.