The people who are actually expert usually don't have the same kind of motivation to get their voice heard above the noise.
Interestingly, a lot of people know who the real experts are. I sometimes wonder about why most systems focus on the internal to the exclusion of any real world input.
I've had some discussions with the lobste.rs folks about another attempt to do a sophisticated trust metric, but nothing ever rose to the level of "we should do this."