There is some merit to this observation. Frederick Wilhelmsen[0] criticized Great Books for this reason, that not only was it selective and culturally restricted, but that it tends to degenerate into a he-said-she-said sort of relativism and leave it at that with no real finality to the whole thing. (Some will likely counter that philosophy isn't about the truth but considering "ideas", but that's nonsense. If we consider ideas, it is only because we are trying to determine if they're true and no other reason.)
Incidentally, it did not escape my notice that medieval philosophy appears nowhere on this list. This is preposterous. To venture from the ancients to the moderns while skipping over Scholasticism is lunacy. I don't necessarily blame the author. There may be a general ignorance and silence about the medieval period at may universities.
[0] https://theimaginativeconservative.org/2017/09/great-books-e...