Embar (Govindan Bhattar) and KurathAzhwan are among the 74 simhasanatipadis. Embar turned to siva baktha for some time and then brought back to SriVaishnavism. KurathAzhwan remained a SriVaishnavite. While Embar is considered to be among OrANvazhi guru paramparai (Guru paramparai of Tenkalai), KurathAzhwan is considered as acharya only and not among OrANvazhi guru paramparai.
What is the reason?.