1. Indie rock has depended on rock crit much more closely for survival than have genres such as pop, dance music, R&B, country etc. all of which have alternate means of finding their market (the radio, the club/dj endorsement etc.).
2. And insofar as the above is true, it’s also true to say that the status of the rock critic is elevated w/r/t indie rock. Britney, Beyonce et. al. were going to be big no matter what was written about the quality of their music, whereas there is strong evidence to suggest that, say, Pitchfork “broke” The Arcade Fire to the public by pushing them so hard.
3. To the extent that indie is, by and large, not experienced socially (except at live concerts and perhaps increasingly through film and tv soundtracks…) the crit (and crit-like-discussions) becomes perhaps the primary means by which people can seek to share their experience of the music.
4. The above are all mutually reinforcing, in that (1) people look for new indie via music criticism; (2) they therefore pay attention to what the criticism is doing and saying, (3) the language and forms of music criticism seep into their own discussions until they are essentially engaging in amateur rock crit (but is there any other kind); and (4) they start to take seriously the debates and crusades of music criticism, such that they feel obliged to e.g. “have an opinion” on the new Animal Collective.