And you did whatever he told you.

The justification for accepting the interpretation of Chazal (regarding legislation, I understood that it was based on Rambam and Ramban) is from the verse and did whatever he ordered. I have several questions on the subject: A. Why does every person called a Tanna or an Amora necessarily say that he is such a genius, what is the difference between us and them (as far as I understand, today's generation is much more rational), and besides, why did they reserve the rule for the period of the Amoraim and Tannaim, why don't we start interpreting it ourselves?
B. From what I understand, the verse is specifically talking about the Sanhedrin. Is this an extension of the Chazal themselves, and if so, is this not the desired assumption (an interpretation of the verse by virtue of which the Chazal derive authority to interpret the rest of the verses)?