Nested Loops Aren’t the Problem. This Is.

Arjan addresses the common issue of deeply nested code, explaining that the problem is not the loops themselves but how the data and responsibilities are modeled. He walks through a practical refactoring example where nested `for` loops and `if` statements are replaced by better data structures, such as using a dictionary for lookups and introducing domain-specific classes. By moving logic into properties on the `Order` class and delegating tasks to single-purpose functions, the code becomes more readable and maintainable. He concludes by stressing the importance of evaluating code based on 'reasons to change,' ensuring that each function or method has only one responsibility. This structural approach not only simplifies the current code but makes it more robust against future changes in data or requirements.