The problem is that stoic people can suffer a serious social penalty to their interests and the cooperation they get from others. It's expected that, once you are in a bad situation, you fight in an outwardly visible fashion. If you don't display the markers of frustration in an easily understandable way, people will think you just don't care enough. Meanwhile, there is little downside to histrionics and unreasonable demands, putting the stoic at a severe disadvantage.