Diplomacy is always part of a multiplayer game, even at always war settings I guess, but i can see the point to use that settings to get a more fair game.
That's not exactly true - it's the common way of playing on CFC, Apolyton, etc - but in other Civ communities any form of talking between the players are actually prohibited. Realms Beyond for instance have a strict no-talk policy in their games where the only form of diplomacy allowed is what you can do by in game diplomacy, like offering trades etc - but even then you are not allowed to type anything in the in game diplo window. So no NAPs, no alliances, and so forth, except what the game offers (resource trades, forced 10 turn peace treaties, cease fire, gpt and gold trades is basically it, since city trades usually are also forbidden in most MP games). With Always War on even that aspect is removed, and there is no diplo whatsoever. Some players feel that this is the purest/fairest form of Civ MP, as it eliminates possibilities like an average player allying with a good player, and that team eliminates the best player because they form a 2 vs 1 alliance - thereby leaving the players (or teams) relying purely on their skills at managing their civ. Don't get me wrong here, as I am not advocating that this is a better way of playing the game than with diplo - personally I enjoy both, and I can easily see how some players prefer one of these ways over the other (that goes for both playing with and without diplomacy allowed). One of my favourite forms of Civ MP gaming is the diplo-style gaming Apolyton is known for with RPing, but that is a completely different way of playing Civ from e.g. the ISDG.
However changing the settings in an ongoing game is problematic. Diplomacy and strategy created the current situation, we can't just change it in one turn. I can see the benefits for you, but not for us for sure.. except I too wish to not continue this game for too long.
Altering the settings/rules of the game at this point is not just problematic, but pointless. The game so far has been played under certain terms and conditions, where diplomacy is the deciding factor in how the current state of the game is. If we remove diplomacy now, that doesn't change anything about what happened earlier in the game - where the current situation in the game would have been
completely different now if diplomacy/talking between teams had been disallowed from the very beginning.
It's better to either finish the current game under whatever terms you players agree on, with the already established rules and settings, or take up my offer on a new game with more to-the-point rules if you want to fight it out with more fair conditions.