Most StuG Battalions/Brigades were organized from the artillery arm, and although the vehicle was pressed to fullfill the role of a Panzer late in the war (in actual tank companies), the Sturmgeschutzen were mostly weapons of the artillery.
I imagine the role of providing direct infantry support as well as anti-tank work required quite a degree of tactical skill and expertise.....this was the duty of the assault guns and their crews, and they were often the first in and the last out........too.
