The letter of the Chazo’a regarding the obligation to obey the elders of Israel. What is its origin?

Hello Rabbi,
I recently came across the famous letter of the Chazo’a regarding the obligation to obey the elders of Israel. I will quote: “The method of dividing the Torah into two parts, one part teaching on prohibition and permission, and the second part teaching on the market of life, to submit to the sages of the generation in the first part and leave them free to choose in the second part, is the old method of the species in the decline of Ashkenazi Judaism, who expelled the people of Israel until they mixed with the Gentiles and there was nothing left to escape.”
I didn’t understand his words, I didn’t understand where he derived this obligation from. I thought perhaps it was a lesson from history, but an active source of the obligation to obey the great men of Israel is still needed, a Sabra or another source from the Holy Scriptures.
What is the origin of being submissive to the sages of the generation in matters of Halacha? The meaning is to be submissive at times when the law is not so clear and one of the great men of the generation has made a decision, so the root of the love of wisdom is to believe that the sage is right if I personally have not received a decision, and so also in matters of life. This is the meaning of the word.
But I didn’t understand the connection. The great men of Israel have great knowledge of the Torah and are wise in this wisdom, and therefore they can rule by it. How could they have clear knowledge of the affairs of life? They did not study business and social life, and even if they did, we do not have clear knowledge that they actually have an understanding of the public soul. I really have difficulty with these words of the Chazo. If it were another person, I would ignore them, but since I have great and incomparable respect for the aforementioned great men, I would be happy to understand the Chazo.
In general, I think that from a perspective that does not appreciate the Chazo, this letter is ridiculous. In fact, the Chazo in this letter demands control over the leadership, which is what I mean by preaching…