Chaucer has been banned in the past.
So has Rabelais and Balzac.
Here's a list of books most challenged (and many banned) in the 1990s in the US:
That's well before your 2015 assertion.
You're aware of the Hays Code dealing with movie content from 1934 to 1968 before the advent of the ratings system (which is a censoring system, in itself)?
I don't think you're aware of how much you're mistaken about history, censorship, and content banning made by both public and private entities.
Heck, a simple Google search will have this as a result:
List of books banned by governments
You must be registered to see the links
You're going to see a lot of dates prior to 2015.
EDIT: To add, your own example from "The Music Man" destroys your thesis... the Pick-A-Little ladies were bitching to Harold Hill that Marian allowed books in the library they did not want: “I shouldn’t tell you this, but she advocates dirty books… Chaucer… Rabelais... BALZAC!” Had it not been for Marian's advocacy - those ladies would have had those books (and many others) removed from that library.