Is a Mursal Hadith considered authentic if it is narrated through two Mursal chains, and why do scholars deem weak Hadiths that have been narrated through multiple Mursal chains?

The function of the Usuli (scholar of legal principles) is to clarify the proof by which rulings are established, and this proof may be found in the statement of a Companion, or in consensus (Ijma'), or in the language of the Arabs, or in other sources. The Usulis' reliance on the Mursal (uninterrupted) Hadith, subject to certain conditions, does not necessarily imply their belief in its inherent authenticity. Imam Al-Shafi'i accepts the Mursal Hadith and uses it as proof if it is narrated through two Mursal channels that corroborate each other, and if its narrator (the one who omitted the Companion's name) is one of the senior Tabi'in (successors). The Munqati' (disconnected) Hadith, as Al-Shafi'i explained in "Al-Risalah," is considered valid if it is supported by the participation of trustworthy حافظ (Hafiz, memorizers of Hadith) or if it agrees with another Mursal narration, or if it concurs with a statement of some of the Prophet's Companions. Ibn Kathir clarified that the Mursal narrations of senior Tabi'in are a proof if they come from another source, or if they are supported by a statement of a Companion, or by the majority of scholars, or if the narrator of the Mursal does not name anyone except a reliable person. Nevertheless, Al-Shafi'i's opinion does not obligate others to follow him.