People Aren't Demos
Being a 25-year-old woman isn’t a universal experience. Nor is being a Hispanic man or a Catholic beekeeper. People with similar demographic profiles have different talents, interests and personalities. And people who share similar attitudes and beliefs tend to behave more alike than people who share a demographic.
Even when demographic correlations exist, it is rare that everyone in that demographic is a customer or that every customer fits the demo. Moreover, it isn’t the demographic that is important. Femininity is associated with prudence, seduction and nurturing; youth is associated with vitality, energy and a free spirit. It’s the association, not the demo that attracts people.
Demographics don’t define either the target’s motivations or a company’s intent, which is why they produce ubiquitous images of smiling [insert demographic profile] using a product.