Knowing that Sarah is a 56 year old woman with a high paying job commuting daily to and from London’s financial district is probably going tell you that she is likely to read the Financial Times. But it is not going to tell you why she reads it, which topics are most important to her or how she uses the information to make better decisions.
Demographics aren’t customers they are proxies. They expose us to biased assumptions about who (affluent, woman, 50-60yrs) wants what. But they don’t help us understand why they want it (or how).
People aren’t motivated by who they are they are motivated by what they need. Customers don’t care about the artefacts companies are selling. What they want are the outcomes the objects help them achieve: people hire products and services from companies to enable behaviors that unlock their need for progress or help them overcome a struggle.
Knowing that Sarah is 56 years old is as irrelevant as knowing that her weight is 67kg. More helpful is knowing what she needs. How she makes decisions and how she measures her own success? This is jobs-to-be-done.