You are missing the critical component, the double spend protection. Which is exactly the world we had <2008. It is powerful and we used it in finance for decad

You are missing the critical component, the double spend protection. Which is exactly the world we had <2008. It is powerful and we used it in finance for decades. However trustless systems that prevent double spends are more powerful, and that is why people are excited. Legal statements are just strings. They mean nothing outside their jurisdiction and only enforceable by violence in them. ECDSA signatures and PoW blocks can be validated anywhere in the universe.