Why is this a popular idea? I was discussing the recent school massacre with my co-worker, with her claiming everyone would like to get violent after being treated a certain way. I claimed otherwise and gave an example, with her refuting the idea - I'd just get violent some time later. Someone wouldn't feel violent at all? He would just be repressing his violent traits.
I tried to hint about different psychological behaviors, with someone getting depressed and the other person getting anxious over the same incident. She didn't listen to me long tho.
It's not an isolated incident. Why do people maintain the idea that one internal psychology fits all? It really doesn't. It doesn't mean that everyone's just an individual and there's no unifying factors, either.
I think this line of thinking might result from inadequate exposure to conflicting emotions. If someone always resolves their problems by eating blueberry pie, then hurrah, your problems are always resolved by eating blueberry pie, and that's the way things are.