Why was the school of thought of Imam Ja'far al-Sadiq not considered a jurisprudential school of thought for Ahl al-Sunnah, despite Imam Abu Hanifa studying under him, and Imam Ja'far al-Sadiq loving and revering Abu Bakr and Umar?

Imam Ja'far ibn Muhammad was an Imam among the Imams of the Sunnis. Abu Hanifa, Malik, and others learned from him, and his statements were considered authoritative by the People of Sunnah. Al-Dhahabi described him as the Sheikh of Madinah, and Abu Hanifa said of him: "I have not seen anyone more knowledgeable in fiqh than Ja'far ibn Muhammad."

The reason for the lack of widespread adoption of his madhhab is not due to him not being considered an Imam, but rather because Allah blessed the four Imams (A'immah al-Arba'ah) with students who studied under them and propagated their madhhabs. Many Imams, Companions, and Tabi'in did not have followers who became famous, nor were their sayings compiled in separate works, and this does not indicate a lack of regard for them.

Whatever is authentically transmitted from Imam Ja'far through trustworthy narrators is considered authoritative by scholars. As for what innovators attribute to him, it is rejected because it contradicts the sacred texts, knowing that he was among the most diligent in following these texts.