My home, built in 1958, has cut nails securing the hardwood flooring.
I hadn’t even considered that this was very old-fashioned, figuring that it must be the appropriate nail for hand nailing hardwood flooring.
The house isn’t anything special, made with cheaper materials at the time. For example, the walls are 3/8" Sheetrock instead of the more modern and durable 1/2". It’s not like those nails were used for some special purpose; they were likely what any builder of tract homes would use in 1958.