At the start, you point out a practical concern for actors: We cannot anymore click on the transfer call and have a look at the implementation. At the end, you highlight an amazing power for streams: We decouple our software: a Producer truly doesn't have to know about its Subscribers. Aren't these the same thing? Also, I'm not sure what you mean by "actors have to know about each other" but Akka has adapted response interaction pattern (hashnode says I can't post links).