Well, you need to define your objectives. No system is robust to a failure of all its actors. If every user (and even developer) is ill-intended, no system will give good results. So we need some "hopeful" (and accurate) assumptions.
One might be that the typical user can sensibly elect a few individuals to trust -- it could be developers (which are a natural choice for trust), to activist and publicly visible individuals (even close friends). Then presumably you could adopt his trust model (such individuals could be roots in independent conservative trust webs/graphs). I think a very large number of such webs might be computationally expensive, but hopefully you'd be able to find someone you trust or start your own independent graph (if you trust no one, you'd effectively lose all anti-SEO measures I guess). This very naturally leads to a decentralized reputation system!
One might be that the typical user can sensibly elect a few individuals to trust -- it could be developers (which are a natural choice for trust), to activist and publicly visible individuals (even close friends). Then presumably you could adopt his trust model (such individuals could be roots in independent conservative trust webs/graphs). I think a very large number of such webs might be computationally expensive, but hopefully you'd be able to find someone you trust or start your own independent graph (if you trust no one, you'd effectively lose all anti-SEO measures I guess). This very naturally leads to a decentralized reputation system!