During their closed alpha (or was it beta?), Spotify’s library consisted of some sort of superset of the (illegal) music collections of their staff. If I recall correctly, you would even get hits by searching for scene release groups in the search bar.

Once this ended and they went legal, I left Spotify and never looked back as about half of my music library was gone overnight. It taught me a valuable lesson early on in life about subscription services and “not owning” your digital files.