Are those who followed their scholars from other sects excused for not seeking the truth, and is intellectual discernment and investigation of facts obligatory in this case?

Permissible disagreement does not apply to matters upon which there is a consensus in religion as a matter of necessity. Rather, ignorance is excused for those whom the proof has not reached, based on the Almighty’s saying: "And We would not punish until We send a messenger." Among the legitimate impediments considered for the proof not being conveyed are the inability to comprehend religious discourse, the presence of ambiguities, and the ignorance of common people regarding the state of misguided leaders. However, this does not exempt them from the obligation of being informed about the misguidance of their leaders.