The thing that killed HMV was the fact the 'new' players just kept improving their businesses - investing in new features and perfecting the way their sites work.
Because, HMV went under because of Amazon and iTunes. Because… you know. Digital, mobile, the shiny future is here today, while the old school is already a thing of the past.
Two data points that don't fit with the narrative are that digital music is still less than half of all music sales, and the majority of DVDs and CDs are now sold by supermarkets. So lets just disregard them and blame Spotify.