I never found it particularly useful but the CIA World Factbook seemed to have originated with some of the "country orientation guides" that the US DoD used to prepare in printed form for military service members being posted to weird locations. There's historical "Welcome to South Korea!" type documents that make an attempt to orient "never traveled outside of the USA before" type Americans to cultural and regionally specific things in Japan, South Korea, Germany, etc. The CIA World Factbook was just a more structured encylopedia like version of the same.

edit: There was absolutely nothing "CIA" specific or sensitive about it whatsoever, it was basically like if you paid some government employees to attempt a job similar to the mid 1980s era Encylopedia Britannica. Maybe with a bit more emphasis on public statistics like literacy rate, percent of houses with telephones, economic statistics, other basic public stats that governments are known to publish.