[abdullahkhalids]

Large publishers are optimizing their overall revenue/profit, not the revenue/profit per book. Given that large publishers dictate a significant fraction of what appears on bookstore shelves, how concentrated publicity drives of new books/authors drives their sales at the expense of old books/authors, and how the emergence of second hand books outside their control drives sales in different categories, its extremely likely that the advantageous strategy often is to not print older titles even when there is demand for them.