In Oregon these types of houses were known as box construction. See if your library has a copy of "Space, Style & Structure", vol. 1, published by the Oregon Historical Society in 1974, now out of print. Chapter 2, pp 98-99 has some information & photos that you may find interesting.
I too believe the chimneys were built this way to save time & money. They didn't pay much attention to "clearance to combustibles" back then. Down here in the Willamette Valley, examples of this type of construction are becoming harder & harder to find & some people have a misinformed notion that it's shabby type of construction, even though the one that are left stiil stand pretty straight & square.