I'd be willing to bet that in looking deeper you'd find it's Spotify doing the lion's share of that.
Only after publication on news sites they fixed it.
Won't be surprised if the bug regressed and happened again.
I don't use Spotify (not available in my country), so I wouldn't know, but I bet half of the reports are because of some badly written third party app constantly writing in 4kb chunks with O_DIRECT or fsync() all the time.