It is alarming to think that Spotify could (inadvertently or even willingly) fill the hard disk of 40 million users worldwide.
However, this can be mitigated by setting "Maximum Database Size" limit on the SQLite database named Mercury.db.
https://www.sqlite.org/limits.html
"Do not seek to follow in the footsteps of the wise. Instead, seek what they sought." - Matsuo Basho