Are scriptures like Bhagavad Gita necessary for self-realization?

Spiritual knowledge is inherent within us but in a dormant state. Scriptures gives us the guidance, techniques and process to awaken our spiritual knowledge. For example, data is within a database. In order to generate insights from the data, one need to know how to write relevant queries. Authentic books show us the way to write those queries.

Scriptures are those authentic books that tell us how to write relevant queries to awaken our spiritual knowledge. Scriptures are either the documention of God's spoken words or spiritual realizations of saints who realized God. It is unfair to discount the value of scriptures.

I would personally put faith in the documented realizations of elevated spiritual saints in the form of scriptures rather than on one Guru.

Hence the realized words of an Acharya never conflict or delineate from what is said in the scriptures but rather elucidates the what is said in the scriptures.