Why the Spread of Book Banning?

From a New York Times story by Claire Moses headlined “The Spread of Book Banning”:

Book-banning attempts have grown in the U.S. over the past few years from relatively isolated battles to a broader effort aimed at works about sexual and racial identity. Alexandra Alter and Elizabeth Harris cover the publishing industry. I spoke to them about what’s behind this trend.

Claire: How did book-banning efforts become so widespread?

Alexandra: We’ve seen this going from a school or community issue to a really polarizing political issue. Before, parents might hear about a book because their child brought a copy home; now, complaints on social media about inappropriate material go viral, and that leads to more complaints in schools and libraries across the country.