In Kutub al-Sittah and all of the four sects of Islam, including the Shia as well as in Christianity and Judaism, there is a belief in the Mahdi. One who attempts to make the Mahdi system appear as problematic or unrealistic would be denying all these faiths and works.
We should do as God says, what our Prophet (saas) says, what his companions say. Were there sects at the time of our Prophet (saas)? Were there sects such as Hanafis, Hanbali, Maliki, Shafi'i, Shi'ah and Wahhabism at the time of our Prophet (saas)? No, there weren't. In order to avoid the damnation of God, we need to return to the pure and real religion of God, to the Qur'an.