From an old conversation in Slack:
Being able to spawn a single purpose blockchain allows massive scaling as there is no need to entangle each chain with the tx from all the other chains. Instead of having a single centralized blockchain for everything, this approach decentralizes the decentralization. The problem is that the security for these small chains would be low, except the delayed-PoW method will allow BTC hashrate to secure all of these chains, creating a common heartbeat clock. That also allows all chains to atomic swap, knowing the boundaries are aligned.