I think part of that is based on Christianity; the idea of God planting a soul into each person. The soul being the “I”, the ego, the individual.
Even if the Eastern philosophers were 100% correct, to function, human beings need a reference point for orientation in the Universe. Figure-Ground reference is used in psychology to for perception. Our basic reference point is the self with an orientation to family, friends, neighbors, state, country, culture, etc.
In keeping with Eastern philosophy, it’s good to remember there is a greater existence than the self. Using 1/6 as a reference, there where a whole lot of “I’s” out there, what’s best for themselves, and very few who thought about what’s best for the nation.
https://www.verywellmind.com/what-is-figure-ground-perception-2795195
Figure-Ground Perception in Psychology
True.
I don't think the Eastern traditions were intending to unmoor us from a sense of grounding. It was just a different perspective on the reality of existence.
Of course Confucianism emphasized familial piety, duty to family and state. So lumping all the East together is a stretch too.
But there really is no widespread western equivalent to the Hindu concept of Atman is Brahman, the Buddhist concept of impermanence, or the concept of becoming one with the Dao in Daoism. Christianity, Platonism, Humanism had a very strong focus of "I", as in the permanence of the individual self.