I thought I’d clarified this. I apologize.
Accepting Joseph Smith as a prophet is incidental. The prerequisite to salvation is accepting the fullness of the Gospel.
The logical consequence of that is accepting Smith as a prophet.
A = C. B = C. Therefore, B = A. According to LDS doctrine, you must accept the Gospel to receive salvation. A = C. Joseph Smith preached the Gospel. B = C. Therefore, to receive salvation, you must accept Joseph Smith as a prophet. B = A.
I cannot be more plain than that.