It was always part of the game because it is so hard to get 7 players to sit down at a table for 7-10 hours to play diplomacy; even with the internet where we can play with 24 hours per phase, some people still drop out. If the game only took 40 minutes (like, say, memoir '44) this wouldn't be a problem. Virtually no other game has rules for what to do to continue playing in this manner, but diplomacy has always had it.
And beyond that, tactical use of a civil disorder can be useful, you can pretend you have to leave and make an enemy alliance think you're going CD which may result in them squabbling amongst themselves instead of attacking you... though extremely risky, in the table-top version some people have been known to take extreme measures - on webdip there are players who keep close tabs on who has entered orders, so that they can take advantage if their neighbour is about to NMR.
@MinisterOfWar, if all players CD then nobody is playing the board, and infact it isn't a game - it doesn't progress via the CD rules because there is no-one to note the turn has changed (or on this server, i suspect that the game is cancelled and deleted)
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Starting Games with BANNNED Players
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