Fully agree. A diagram is ok to describe a flow, but for complex code or systems, round tripping is a necessity, otherwise the diagram is or quickly becomes inaccurate and worse than useless. In the 90s I tried software called TogetherJ, it seemed to support round tripping really well, so well maintaining code was the same as maintaining diagrams, and led to better quality in both, along with documentation and other benefits such as relaying higher order concepts. I just did a search for togetherj and the only reference I could find was a 20 year old forum mention. Weird. I suppose there must be high end enterprise CASE software that still supports this approach, though I'm guessing most people abuse it so it's no longer respected. I think these things happen in cycles, as we can 'orchestrate' larger systems with meta descriptions of components, they become more valuable.