Until we get some kind of lid on complexity, I don't think real engineering will happen. If any abstract box in your diagram can be arbitrarily complex, then i

Until we get some kind of lid on complexity, I don't think real engineering will happen. If any abstract box in your diagram can be arbitrarily complex, then it's not going to stay in that little box. It will develop tendrils into logging and error mechanisms, and start to find extra jobs it can do with extra connections to other components. Pretty soon the semantics of the box will be so complex that they can't be reproduced elsewhere, and you will have to use that box for all kinds of new tasks. I imagine a database was, at one time, just a little box on someone's diagram. Now it's Oracle Spanner RAC Mongo Hadoop and must be used by every line of code in the world to get anything done. That's why a diagram is useless (EDIT: useless as a prescriptive language, but still useful as a descriptive language.).