Why need not all preceding words match in “marfūʿah / mawḍūʿah”?

Sajʿ and Muwāzanah: Rhymed Prose, Rhythmic Endings, and Balance

• Because weight never matters in sajʿ
• Because there is always only one word
• Because mutawāzī primarily compares the end words
• Because the example has no fāṣilah