Indeed an actor only model will easily lead you to a mess. At first it's simpler with actors to think concurrently mainly because of the strict message passing

Indeed an actor only model will easily lead you to a mess. At first it's simpler with actors to think concurrently mainly because of the strict message passing rule for communication. But as your logic become more complex it will become hard to understand as the code flow is artificially separated between different entities, that doesn't scale nor compose easily. That's being said, it can be powerful to have just some top level actor abstractions that encapsulate more common idioms. Actors are great to build distributed micro services, you can have a supervisor to monitor and restart services, a registry to discover and subscribe. An actor can represent a service of course. Very useful as high level concurrency abstractions, not so much as low level primitives.