The Gregorian calendar was adopted by most Roman Catholic countries.
Many protestant countries did not accept the new calendar until the 18th century, including Britain ... The British finally accepted the Gregorian calendar for itself and all its possessions effective March 25, 1752.
Furthermore, prior to Deja News, most participants in Usenet discussions thought of their postings as ephemeral.
The thousands of distributed Usenet News servers at universities, ISPs, and companies usually archived newsgroup material for no longer than a week or two.
Over time, Deja News built an archive of Usenet postings that lent a sense of permanence.