Some people found out that legitimacy is implied by coordination and started using cryptography to build various ways to coordinate multiparty computations that can simulate various banking/finance protocols.

Web3 is normal web development where you use some APIs to interact with these protocols and condition access to {functionality,resources,..} in your webapp on the current state of the multiparty computation. You can also participate in coordinating the computation.. idk maybe I'm taking the 2007 constraint a bit too far.