Everyone knows how much their rent and car payment is but most other stuff people have no idea. A lot of people don't even want to look at the numbers on their own so they need someone they can trust to help them face the reality.
Having someone who can sit you down through the process of accounting for every dollar, calls out areas where you're over spending, and helps you create a realistic balanced budget is very valuable.
Plus, there's other things like understanding the most effective way to pay off your debts, how much you could actually afford if you wanted to buy a house or a car, and understanding how to build wealth. Most people lack these skills but are very successful once they learn them.