How did they drive nails into hardwood before modern power tools?
How do you get to Carnegie Hall? Don't discount the fact that everything was hand nailed at one point. Sheathing a building in board by hand works wonders for increasing efficiency with a hammer. 

One hundred years ago green or air dried lumber was the norm, rather than kiln dried. Even seasoned lumber had generally been in the air under a year at the mill. Wet lumber is substantially easier to work with than dry, which includes nailing. (Solid wood is also easier to nail than composite or engineered lumber, which can skew perceptions if you're used to modern materials.)