This tends to be true of mamy of the artists that chart, but less so for indie bands. I see Major Parkinson's Blackbox and Magna Carta Cartel's The Dying Option as two of the best albums of the century so far, for example.

That's nothing new though, a lot of the big name artists' albums are a collection of most of their singles (idk how the album vs single market works); e.g. Taylor Swift with 7 singles made from the 13 tracks on '1989'.

I don't know what is normal, but releasing singles or EPs before the full album seems like a common way to generate hype beforehand. Also, the Spotify model - assuming against what the previous comment says and every stream counts for the same revenue - doesn't differentiate between singles, EPs or albums, so it's whatever from that point of view. I've seen a few artists start releasing demos, songs-that-didn't-quite-make-it, and all kinds of unusual material that wasn't good enough for a full album onto streaming platforms, which then ends up in the long tail of their repertoire. It ties in with the article though, in that these songs will also start appearing in the playlists related to those artists.

Another interesting one is a single artist releasing songs under different names; Devin Townsend comes to mind, who can fill up a related playlist with songs released under his own name, Strapping Young Lad, Devin Townsend Band, Devin Townsend Project, Casualties of Cool, etc. And given he does many different genres, he'd appear - theoretically - on many different styles of playlists too, although I think the algorithm would get confused when the artist name gets associated with both hourlong ambient tracks and seven minute chaos metal genre mashups.