the problem is that if you stick your stem on your steerer and it doesnt reach the top bolts middle,you´re gonna apply more tension to the upper clamp area than on the lower(or vice versa if you DONT bang it tight),resulting in a pressure difference right in between the 2 areas.
normally theres tension only applied in horizontal form,giving "more room" for diagonal force peaks to apply,i.e.when pulling the front up,if you tighten the areas differently,you get horizontal,diagonal and axial forcesapllied without doing anything,in still position..
this is called triaxial state of stress and will lead to material failure for sure.
only the construction of the stem and the steerer itself will determine the time elapsing until....crack.
lever x force x 3(in diagonal and axial direction)... i wouldnt go that way.
source:a friend of mine,metalurgic technical assistant