Offline mode on spotify is local media with extra steps. Offline mode is premium only. Also you still get tracked with the proprietary app. Spotify songs cannot be played in your favourite music player, device or whatever. I can copy some songs into sdcard to play it on an old speaker set.
Pirated music gets more convenient than what you paid for. Moreover, restricting saving and sharing media is kinda dumb and does not actually hurt artists or their revenue