Things has changed a lot for why reviews could be relevant and what for they are.
I don't think reviews nowadays function for "boosting sales". While in old days, the means you had was to play shows, get press attentions... and... ? Well, now you simply don't. You can post link to mp3 sample directly to customers.
What review now is worth, especially in format of magazine, could be written statement what remains as document of passing time. When next generation tries to find out what happened or you look back on history, you won't remember the endless stream of myspace sites and bandcamps, but you might remember the recordings you bought and recordings what you read (hopefully) well written piece. From 100 releases of 50 copies CDR's and tapes, the ones that will stay in collective memory, will be most likely those that were documented. Disappearing blogs, old forums disappearing etc.
At least I know plenty of people who return year after year to their old magazines or books. But how many will read review of webzine or mailinglists that came out 10 years ago? If that even exists anywhere anymore?