Stereotypes have been given a bad name. But the reality is that we deal with most of our world in the form of stereotypes. Using stereotypes saves huge amounts of memory space. Stereotypes can also be cascaded. If I see an angry Chinese schoolteacher, I can draw from my impressions of angry people, of Chinese people, and of schoolteachers, to give me a more precise feeling for what to expect of the person I am about to encounter.
Stereotypes can be overridden for individuals one knows.
As one gets to know us, though, the stereotypes fall by the wayside in favor of a real file, with real data about us. And that file will probably be anchored by the face. Thus, many close people get processed in the way strangers are by the majority. So we need to consider how strangers are processed, and that is with stereotypes. In fairness to face blind people, it should be said now that the face blind are far too busy juggling categories of people just to tell them apart.