Why do none of the US doctrines have the mobile howitzer, the scott?

Why has the M8 Scott not been included in any of the US doctrines? Speaking of that, I have discussed this with Meatshield and Mongalong, but never received a firm answer. Are you planning on adding the quad .50 to one of the US docs? It is in the game already, as is the Scott. One area where there are no differences between the US docs is the light vehicles. Are you intending on changing any of that around? You do get the M20 command car, instead of scout car, for armor doc, but I think that is it. Otherwise, all docs are the same for light vehicles. It would be cool if they differed a little. Perhaps you are saving the Scott for arty doc, but there is still the quad .50 that can be added, not sure of anything else. Maybe only give greyhound to infantry doc, or something like that, as long as it is a little different, it would be cool. Thoughts?