The chess analogy is bogus. There are variants in chess. I play nightmare chess nd four way chess and 3D (i.e Star Trek) chess all the time. If the team play were a variant, it could be combined with a more global WWII variant (think Axis and Allies without the dice) where Russia (and only Russia), starting as an Axis power, could switch sides at his choosing, making the diplomacy with Russia very important. So less a feature and more a variant capability.
I only mention this because the point system is also not part of the classic game. In the clasic game, it's winner take all unless you declare a draw, but here we have points (D) that go to victors and survivors and are split evenly in a draw. This aspect of the game alone means it is no longer classic Diplomacy. Calhamer's rules never mention anything about winning points or D or whatever you want to call them. So, if we are adding this dimension to the game, we can add others.
So, Ivo, before you insult me again, you should re-examine your statement about the "pretty old game" and the "defined rules". The game we play on here is not that old, only as old as the site, as a whole new dimension was added. And those "feature requests" that change the nature of the game? Don't you agree that having the (D) changes the nature of the game? If you fail to understand why, then you are not qualified to make such a judgement of me in the first place.