Eh, I think it's a bad idea to ban any type of speech, even hate speech. If the government does it, it's unconstitutional, and if a forum does it, it kind of just ruins the quality of banter, something that we should try not to ruin, and adds subjectivity (i.e. "what is 'hate speech'?"), where I much prefer objectivity.
@steephie - "Arguably, it's against the spirit of the game because people may pursue suboptimal results because of an alliance."
But in my opinion the spirit of the game is also forging alliances. Now, I'll admit that I'm too much of a "carebear" myself and should stab more (it's my pacifist tendencies manifesting themselves in the game), but there's something to be said for a successful partnership. The key, I think, is balancing when to be ruthless and when to work together.
@jbalcorn - the official definition of carebear to end all definitions: "a Diplomacy player who values loyalty to allies over their own best interests and thus stabs far too little." They're the best kind of ally, and if they're good they might not lose much, but they rarely ever solo games.