«زَيْدٌ شَاعِرٌ وَعَمْرٌو كَاتِبٌ»
Zayd is a poet, and ʿAmr is a writer.
Coordination becomes more meaningful when Zayd and ʿAmr have a recognized relation—perhaps they belong to the same literary circle, or the conversation is comparing their abilities. Poetry and writing themselves are also meaningfully connected.
If the two people have no relevant relation and the discourse establishes none, the mere fact that both are subjects of grammatical propositions is not an adequate explanation for coordination. Context and shared knowledge are central to the jāmiʿ.