An important bit that's mentioned in passing is that Vulfpeck encouraged sleeping fans to play the silent album on repeat overnight (thus, Sleepify) to add to the playcount coffer. Though this tactic was initially creative and effective (really, hats off to 'em), I do think Spotify were justified in putting a stop to the potential trend of 'silent album'. There would certainly be hundreds of uninspired copycat 'silent albums' with a sole money-making purpose if this was tolerated (Spotify's already dealing with new ridicule for a preponderance of "karaoke versions" and the like mucking up the works).
I also think it's unfair to compare Sleepify to John Cage's "4'33"" as Cage's purpose in 'writing' that piece wasn't to raise funds for a tour. But, I'll go one further and say that "4'33"" shouldn't be on Spotify either … it only truly resonates when performed live: