That article is masterwork, thank you. It seems like having a "hub and spokes" architecture is key to getting event sourcing right. LMAX's Business Logic Processor is the only thing sourcing outputs, so you don't hit dependency hell. Also, your business process is literally a process, rather than living on the ledger.

It reminds me of well-designed Paxos control systems like Borg, where the journal serves as the ledger and all business logic lives in one scheduler thread.