Although prior experience with "medieval wargames campaigns playable with paper and pencil and miniature figures" was an asset in understanding the original presentation so that one might referee the game, it was not a prerequisite for participation as a player.
The beauty of a basis in reality is that everyone is acquainted with it. One need be no student of matters medieval, or acquainted with the exploits of John Carter, Conan, or Fafhrd and the Gray Mouser. The rules are "strictly fantasy", but fantasy of a sort only occasionally so bizarre as Alice's adventures in Wonderland.
With 4E, one has no such foundation. From what I have heard, prior experience with certain video games is an asset in learning the rules ... but learn the rules one must, for there is no other guide.