Have you heard the term “they just don’t make the like they used to anymore”? Most lumber found in the big box stores comes from tree farms where the trees have been selected and managed to grow fast . A lot of the construction lumber is now douglas fir and spruce and pine has long been held as superior for a lot of uses. Fast growth in soft woods means the wood is weaker and less durable when exposed to weather and wear. In Oak however, the fast growing wood is actually stronger but does have different grain patterns from slower grown timber.. Because of the qualities of old growth pine it is often used in flooring and in use in furniture, particularly furniture reproduction.
Since he house was built in 1966 this may not actually be “old growth” pine, but is probably still a better quality that is normally available today.