I woke up one day last year and realized I no longer listened to music. Instead I just listened to sludge—a blur of indistinguishable songs that imitated my music taste. My sludge addiction sprang from Spotify’s algorithmically curated playlists, which promised to help me focus or find music tailored to my tastes. The app’s design was always nudging me in that direction, so I dutifully followed. It was so easy! Searching for good music takes time. But at a tap, these playlists drip-fed me endless pap that dissolved into the background….