In a team setting, this is a result of the team members being ordered to not communicate with opponents by their team's leadership. This is ordered so that the team members do not act like assclowns to the opposing side and ruin their team's reputation in the eyes of their opponent's and the rest of the game's community.
Because of the lack of friendly communication between sides in the game, the side attempting to communicate with the silent side will sometimes bitterly react to the silent team, believing the silent team is arrogant or "too cool" to talk to them.
However, some teams like the Absalom alliance is notorious for not speaking in the shared war forum when at war with a kingdom. Leadership from kingdoms warring an Absalom kingdom generally must contact the leadership of the Absalom kingdom through the kingdom's public IRC channel, then talk through private messages. Opposing kingdoms already know and understand that an Absalom kingdom will almost certainly not speak in the game's war forum as Absalom operates under a Code of Silence, although there have been exceptions to this rule.
"No, don't you know they aren't permitted to by their leadership?
B) "Are they 2leet2speak with us?"
"Idk, they sure seem like a bunch of pricks