It's a bit different than that in PvP, mostly because the person screaming the loudest in Raid/BG Chat has no idea what they are talking about. That isn't always the case, but more often than not it's a key turning, backpedaling whiner screaming "GAWD YOU GUYZ SUCK!".
Maybe the person should know better, but getting a random tell from someone who's acting all high and mighty is going to throw anyone on the defensive. Especially if historically the people who whine the most are the worst players.