Serious question… if you had Spotify or a similar streaming service and you could listen to an album anytime you wanted, as many times as you want, why would you buy the same album on iTunes, Amazon MP3, or Google Play?
In the case of a CD versus Spotify, there’s a quality difference of course. But with an MP3, the only difference I can think of is offline access, but Spotify premium accounts have that as well. So what reason (if any) is there to purchase a download? Answer in the comments.