Subsidiarity is decentralization. You can't consistently abide by the principle of subsidiarity otherwise. The United States has tried, and the result is what is called "marble cake federalism". The demarcation between federal and state lines has become so ambiguous that virtually all programs are odd chimeras of both. State programs financed by federal funds with strings attached, or federal programs that are mandated on states without giving them any special funds for it, so on and so forth.