Why do most populated countries use a federal system?

Most populated countries adopt a federal system to effectively manage the diverse needs and interests of their large and varied populations. Federalism allows for a division of powers between national and regional governments, enabling localized governance that can address specific cultural, economic, and social issues. This structure promotes political stability and helps prevent regional disparities, ensuring that all areas have a voice in the political process. Additionally, it can facilitate better resource management and service delivery across vast territories.