I've never seen a study on it, but I tend to agree with you that more mass = more stability.
The errors you mention: jerking, flinching, torque, are pretty gross errors. One of those errors could easily throw an arrow 8" off target. If having a heavier bow only makes you throw it 7" off target, you might not consider that to be a great improvement. However, let's consider the minor variations we have in releasing the arrow from shot to shot that don't really even have a name. I'll bet that having a heavier mass bow will put more of those otherwise perfect shots in the 12 ring rather than the 10 ring, where a 1-2" difference in POI would make a difference.