الجواب حامدا و مصلیا
The main objective is self rectification. Bai’ath is a covenant of a person who makes Toba (asking forgiveness) and assures to refrain from sins on the hands of an elder who himself is a follower of Shari’a in his practical life and also have the capability of making others too adhere to Shari’a, which is of assistance in self-rectification. Adopting the Bai’ath system is although not Fardh or Wajib in grade yet it is Sunnath.
Allah knows best.