The original rules of the game suggests that the ending winner of a standard Diplomacy game is only one player. The possibility to draw before the end is mentioned, but it's not deepened, and really that's an eventuality more typical of the tournaments than normal games.
The fact that ultimately there is only one winner leads every alliance to be pretty unstable, while giving the chance to draw and split the win leads, in particular in online games, to the possibility of creating very stable and coordinated alliances. With only one winner, the players know that there is no real alliance, because the alliance itself ultimately will never win: only one of the players woulk take all of the points.
So, I have to say that I'm surprised that here there is not the chance to create games in which only one player can win the game. It looks like a very easy implementation, which might work as follows: it's not possible to draw; the game ends when one player is decided, or when the game is canceled, in which case every player receives his points back.
Has this already been suggested in the past? Is there some reason this rule still is not applied? Is it already applied and I failed to found it in the advanced game options? Did I fail to check in the FAQ?