This isn’t to say that there’s no benefit in a business-writable DSL. Indeed a couple of years ago some colleagues of mine built a system that included just that, and it was much appreciated by the business. It’s just that the effort in creating a decent editing environment, meaningful error messages, debugging and testing tools raises the cost significantly.
What Martin doesn’t go on to explain is that this project vastly improved efficiency for a whole organization. They went from a situation where it took months with dozens of programmers to change some business rules in their software to minutes with all sorts of extras they couldn’t get before like “what-if” simulations.