[rabidrat]

Unfortunately if it's decentralized, then it becomes controlled by spamlords, SEO artists, advertisers, and anyone else who stands to gain from manipulating the index to their advantage. At least if it's centralized, the fights are out in the open and have a chance of converging on something reasonable (like e.g. wikipedia).

[snaky]

Decentralized doesn't mean flat. You can trust to some actors only (and to some they trust to).