Sometimes the listener is seeking assurance or confirmation rather than an explanation of cause. The next statement is then framed to strengthen or answer the preceding one, not simply to add another fact.
«قَالُوا سَلَامًا قَالَ سَلَامٌ»
They offered a greeting; he replied with a greeting.
The example shows the independent status of an answering utterance. The two statements clearly belong to one exchange, but the second is a direct response. Meaningful relation alone is not enough to require coordination.