Why is wāw significant in jāʾa Zaydun wa-ʿAmrun yatakallamu?

Appendix to Faṣl and Waṣl: Circumstantial Clauses, Wāw and Pronominal Linkage

• ʿAmr is an adjective of Zayd
• Yatakallamu is a cognate accusative
• The later clause lacks a pronoun of Zayd, so the circumstantial link is signaled
• Every imperfect verb requires wāw