I came across an old (July 2002) article by Annalee Newitz in Alternet ("Reputation System"). It throws light on an interesting property of reputation systems, that unpopular community members are too quickly sidelined. And:
Sometimes we need to listen to people who have bad reputations. Often they are the critics, the people with a talent for seeing flaws and problems none of us wants to face. Communities can't thrive if they never answer to the least reputable of their members. So, for now I'm waiting for a new community system, one whose wisdom will destroy reputations and replace them with something more meaningful.
This was written when mainstream reputation systems were largely centralised systems, where filters work on the aggregate ratings of community members and unpopular members hardly ever rise above the user's filter threshold. Furthermore, unless a user feesl very strongly about siding with an unpopular opinion, or she knows that person well, it is unlikely that she will try and promote these "outcasts" vocally, for fear of losing reputation by association, ridiculed or seen as uncool.
By decentralising the reputation system, however, we are giving unpopular opinions a chance. RSS and decentralised rating models allow each of us to take control of whom we would like to listen to. Ad hoc communities are allowed to form around an opinion or meme which may be unpopular in other circles.
Preferences are also private in decentralised systems, so we can continue to be a fan of an "outcast" without fear of being uncool. Our aggregated RSS feeds, for example, are for our eyes only. But chances are there are others like us - all we have to do is find them on del.icio.us and liking that unpopular source may not be so uncool anymore.
This is the Net taken back to grassroots level again, where such powers are to be found. Decentralisated reputation-enabled systems allow the small voices to be heard again and give them a chance to make impact.