Why is philosophy so overly obsessed with individualism?

Let's for example take Hobbes' concept of the social contract. Hobbes mentions that when people lived in the nature, they were fighting each other and nature, but once they united under one state, they could have a better life. This was made possible because all of the people threatened to shun all the people who disobeyed the rules, so the mass of people could maintain justice on its own, without the need to a state. Hobbes also described this idea of "war of all against all", or the tendency of people to be in a constant hostile behavior towards each other. It's not hard to see why he was wrong, since the war of all against all actually happened when the states existed, not before that.<br>Hobbes also describes the state, or Leviathan, to be an individual. Hobbes describes it to be an entity which has its own power, actions and goals. What Hobbes basically said is that to make people behave, we need to give one individual the power to create and enforce laws, which is the state. The people, or the mass, will obey the laws, and the state will enforce the laws. <br><br>Another example is the utilitarianism of Mill, when he said that the best system is the one which creates the most happiness for the greatest amount of people. What's wrong with this philosophy is that it is also based on individualism, because it doesn't take into consideration the society as a whole. Rather, it describes people as isolated, separate entities, which can live their own lives. <br><br>It's not just them, but it seems like most philosophers describe humans as separate entities, which can live their own lives without any regard to the society they live in. Why is this so?