How can I disable showing iTunes music purchases in iOS 9?
So this the ability to enable/disable showing iTunes purchases still exists, but it's not under settings. It’s right in the iTunes app itself.

Launch the app and then click on the pull down which allows you to select iTunes listings like by artist, album and all that; pic below for reference:



When you click on it look at the bottom of the list. There is a toggle called “Only Offline Music.” Pic below:



Select that and then… Violà! Listings are back to normal again!