Why do many critics treat a Companion’s “from the Sunnah” as constructively marfūʿ?

Isnād, Matn, Explicit and Constructive Marfūʿ, and Mawqūf

• Because “sunnah” always means a Successor’s view
• Because all Companion acts are mutawātir
• Because the phrase from a Companion normally points to Prophetic precedent
• Because it explicitly authenticates a narrator