Who says?.. The Apostles were mostly uneducated teenagers.. Saul/Paul spoke several languages, schooled in Torah, Semantics, Talmud, Politics, Jewish and other Historys, other disciplines, and was a Roman citizen.. God's choice, Mattias was not..
Pauls "Vision" was in more depth and broader in scope.. than the other workers.. How could it not have been?.. God SLAPPED Saul off his donkey(hard) and got his mind right..
The letter to the Ephesians was and is still the deepest thing ever penned by any human at any time about any thing.. Says a lot about the Ephesians..