You can make the same argument about buying MGM.

Looking at Publishers Weekly, I see this:

"An important driver of print book sales last year was the continuing increase in backlist sales, McLean said. Backlist titles accounted for 67% of all print units purchased in 2020, up from 63% the year before. In 2010, backlist accounted for only 54% of all unit sales. " https://www.publishersweekly.com/pw/by-topic/industry-news/b...

I think you could make a strong argument for buying a large publisher (or anything really) given a good ROI.