I think there is some truth to what Jeff says: manufacturer's are going for a 'look' rather than making structural sense.
I have shared on this page my frustration with manufacturers that provide a kit with a neat looking false front, rather than an good side, which is where the railroad ran. Dale Krutzer (apologies for my spelling) makes good use of some Wild West and Raggs kits for a background town, but this tends to be the exception rather than the rule.
I have not made a study of it myself--and in fact it would take some study of historic photos to confirm the rules. I think it would be easier to have the top of the false front align just above the roof ridge beam; extending the false front far above the ridge makes an even larger unbraced sail, and we all know these buildings tended to be built in wide open spaces where the wind has a chance to accumulate some speed.
My nickel, now worth two cents.
Keith Hayes
Leadville in Sn3