It happens to me quite often that players leave the game early (when they see it's lost, or for whatever reason, or they just go afk)
Sometimes, all players have left, and leave me alone against sad AI. Why is it sad ? Because no matter how many territories I've got, I know I will win, and I know it will not be a challenge. (even if it may be long, if I'm weak)
When all players have left, you should be victorious. They capitulate, or they abandon their army. They admit defeat.
Same in the other direction : If I know it is lost, and if I want to abdicate, I don't want my victorious opponent to need to wipe out dummy troops for 15 minutes after I left.
(In case of crash, you can hope to come back soon enough, before every other players have left)