- We mean using one log across different concerns like state a, communication with b, lock c. Often that is in the scope of a single entity (payment, user, session, etc.) and thus the scope for the one log is still small, and it reduces coordination headache for coordinating between the systems. You would have a lot of independent logs still, for separate payments.

- It does _not_ mean that one should share the same log (and partition) for all the entities in your app, like necessarily funneling all users, payments, etc. through the same log. What would be needed if you try and do some multi-key-distributed transaction processing. That goes actually beyond the proposal here, and has some benefits of its own, but have a hard time scaling.