Charles didn't factor in the importance of Composability when designing Cardano and its layer 2 scaling solutions. Atomic composability (seamless dapp-2-dapp communication) is absolutely vital for DeFi. This is the main reason for Ethereum's huge DeFi ecosystem network effects and growth, many multiple dapps being able to interact with one another frictionlessly all at the same time. Unfortunately, Cardano's scaling solutions (Hydra etc.) breaks its network's atomic composability, because execution environments are fragmented when you add layers on top of a network. So sadly things like DeFi on Cardano won't be what it could have been had Charles designed the network with this in mind :-(