Because there's no mixing of applying changes to the state of the system and retrieving the state. Testing becomes much easier and looks like a business DSL on

Because there's no mixing of applying changes to the state of the system and retrieving the state. Testing becomes much easier and looks like a business DSL on the system (also connects well with functional core, imperative shell). Also for the heavy read systems you can easily introduce performance improvements as the read path is separated. Out of curiosity, what issues did you have with CQRS? How was it handled? I would like to know because maybe it was applied in an inconvenient way. Some developers that worked with classical layered architecture for years have a problem with CQRS, DDD and FCIS, but when it clicks it's "Oh wow, it makes a lot of things simpler" moment for them. There are also drawbacks of course and that approach fits well to bussines solutions, so you can't find many applications in OSS, which are mostly technical solutions.