From my understanding, Spotify's recommendations have a major flaw - they're based off other users' listening data. What this means is that if a song isn't listened to by very many people it'll never be recommended, and many songs on Spotify don't even have a single stream, let alone however many it takes to get the data to make it a recommendation.
Luckily, the author outlines the fact that many of Spotify's playlists are curated by humans and when you submit an album to Spotify, you highlight a single track for a human to listen to. It is very possible to catch the ear of a human at Spotify and be placed on playlists, which is a spark that ignites more listenership.
