Conversely, that the mechanism is so old indicates that it evolved to work in groups of the size humans (or their ape ancestors even) formed back when it first appeared - i.e. dozens, not millions. It's not a given that the way we scale it is optimal, or even good.
That's sort of what bothers me. This stuff evolved to work in small tribes, not global societies. When you don't actually know the person the behavior is very different.
