It is an act that lies below our dignity. We naturally associate stooping with being debased or degraded. I am glad to be of help, but never ask me to stoop. The more important we consider self, the harder we find it to stoop. There are people we will not stoop to help.
Examples exist everywhere.
People controlled by their prejudices will not stoop to help the objects of their prejudice. Such prejudice is and has been the foundation of wars from Eastern Europe to the Middle East. Hate will not stoop. Such prejudice is and has been the foundation of tribalism on continents such as Africa for centuries. One tribe refuses to stoop to help people they classify as inferior in another tribe.