Some would call it piracy.
But effectively media from the 80s and earlier, that would otherwise become completely unavailable, or rot, becomes preserved and available for many generations to come.
Though that's secondary to the focus on quality and value of the material.
[0] http://transcripts.wikia.com/wiki/Star_Wars_Episode_VI:_Retu...
'Benefit is up there with MF Doom when it comes to being mysterious. He popped onto the scene in the early 2000's when Napster first blew up, when (by a longshot) he won a rap contest out of over 1000 MC's put on by Napster. This made him the first MC to truly use the internet to blow up (seems like forever ago, huh?). He never really put an album together, just happened to make enough tracks out of his $18 setup to release 2002's Benefit, which is filled with too many dope tracks. ' [0]
I can see how even without the help of a contest, indie artists could use sharring platforms to get traction.