In many cases, all or some of an author'sworks included in this set were unavailable.
One of the primary goals of The Great Books, was to make some of the (especially ancient writers) more accessible to modern audiences with respect to ready availability of their works which were otherwise much more expensive.
This certainly says something about both publishing and reading practices of the early 20th century.
Moller, Violet. The Map of Knowledge: A Thousand-Year History of How Classical Ideas Were Lost and Found. 1st ed. New York: Doubleday, 2019. https://www.penguinrandomhouse.com/books/546484/the-map-of-knowledge-by-violet-moller/.
A complaint more specific to the quantity of books was articulated in 1522 by the jurist Giovanni Nevizzano of Asti (d. 1540) who observed that the great number of available books made it hard to find the books one needed. Proper selection among the many books available was crucial because “if a scholar does not have the books required for his subject, he does not enjoy the privi-leges of a scholar.”20
This same sort of quote is often repeated in the present while vitiating against the corporate publishers who own most of research publishing and charge for it dearly.