Why is "Performing atomic operations on the elements of a collection within a for or foreach loop" a symptom of mediocre programmer "inability to think in sets"?
How should one do that if your "thinking is sets"?
That particular symptom is built under the assumption that your language supports map/filter/reduce or some equivalent functionality. These are generally preferred when available because there are fewer places to make mistakes.
How should one do that if your "thinking is sets"?