I think TW view is that players are not SUPPOSED to win... there is only endless war just like most of the medieval era but I think they forget that occasionally kings did nearly entirely win, Charlemagne, Roger II, Ivan IV, Sultan Mehmed, less than a handful of others but it did occasionally happen and for a game, end state of uniting the the Empire factions to become Emperor and facing an allied group of enemy kingdoms supported by foreign mercenaries and subduing them to become "The Great" is something to aspire to.