Here's my attempt to explain the other examples the author sited, from Diplomacy and KDice (not that I've ever seen KDice).
The Diplomacy action I've seen before, and the real reason for that action (letting the guy who attacked him get his centers) has several causes I've seen. The most common is "I can't win and the sooner I'm eliminated the sooner I can go do something else." Very rational. The next most common is: "If the guy who beat me wins, I feel that's a better result than losing to a guy who didn't win." A third possibility is he wanted to punish those he feels should have come to his aid and did not, which is often far worse than attacking a rival. And yes, fourth is to do the only thing he could do at that point, since he didn't care about anything else. I've seen many players do such things without any prompting from the attacker, including when the attacker was me.
Italy letting Germany write his orders for him is something you see a lot when someone is tactically superior to the other player. Usually in a long term alliance there is talk about goals but the actual orders are being run by one player, and that's as it should be if you have to coordinate. Some games allow the leader to physically make sure the follower is handing in the orders he wrote, and that's awful, but a lot of players don't think ahead to what will happen when they don't want to follow their dear leader anymore. It's also possible that Italy was willing to accept second place, which is a fine result for many people especially as Italy.
On the KDice situation, the game is rather poor as a game. It's not good enough at being Diplomacy to be a good Diplomacy and it's not strategically interesting in any other way except in the very beginning. With the social conventions that evolved it's even worse, and the people who continue to play are the ones who like it anyway for whatever reason. I don't think letting the winner be judge is a bad rule, especially if it's known in advance, and in fact I think that the need to fall in line and win favor from whoever is going to win, once the winner is known, makes the game better rather than worse.
Game theory is great if you know what game you're playing. All this talk of Diplomacy reminds me of this memory of Adam Cadre:
What happened? Why did Italy and Russia fall into line and abandon Austria in the second battle?
This utterly failed to demonstrate the "shifting alliances" that Adam thought the teacher wanted. Does this happen every year?
Yes, the students were coerced into "playing" this game, but elsewhere he describes the same thing happen in games that people choose to play. Moreover, he tells the first story to illustrate his perception of politics.