There are always risks and uncertainties involved during solution implementation. It's very tedious to understand how much time a developer will spend on fixing a bug. A good solution architecture controls the cost and budget and reduces uncertainty by providing developers with the required guidance in terms of priority, different communication services, and details of each component.
Solution architecture also creates documentation for keeping the system up to date, a deployment diagram, software patches, and version, and enforces the runbook to solve frequent issues and business continuation processes. It also addresses the indirect impacts of the cost of building a solution by considering extensibility, scalability, and other external factors that matter to the development environment.