Using events as the input for state update operations in MongoDB can make state-based approaches more efficient. Instead of loading and replacing entire documents, events carry precise business operation data that maps directly to MongoDB's atomic operations like $inc, $addToSet, and $set on specific fields. This avoids the need for diff mechanisms or full-document upserts, and keeps business logic clean and testable. The pattern works even without full Event Sourcing — events serve as a bridge between domain logic and efficient storage updates.
