[hallh]

It's not. The total revenue available for royalties is distributed to rightsholders by the volume they occupy of total plays in a given timeframe[1]. It's been a hot topic for a long time, as your subscription is not going to the artists you listen too only. Huge pop hits that are responsible for X percent of plays across all Spotify streams, will receive X percent of your paid subscription, even though you as a subscriber have never listened to them.

It's a simplification, since 100% of an individual's subscription doesn't go to directly to royalties, it's after expenses.

Smaller artists are frustrated with this model as it favours the big artists.

[1] https://support.spotify.com/us/artists/article/royalties/

Edit: added the link.