So what does Bitcointalk do? Makes a centralized trust network and enforces it by default for anyone signing up through the DefaultTrust network.
"enforces", yeah theymos pointed me with a gun to accept DefaultTrust. Oh wait, I don't trust DefaultTrust
Please do a favour to yourself (and others) and replace the time spent posting nonsense with time spent setting up your trust network.
Personally, I think that it is probably not a bad idea to have DefaultTurst in your trust list as it is a good starting point as to whose ratings you should trust. As you spend time in the various marketplace sections (as well as other parts of the forum), you will be able to determine who is reputable enough to have in your trust list, and add them to your trust list (even if they are already in your trust network), and will see who is leaving trust ratings that you do not believe in (and are in your trust network), and exclude them from your trust list. Over time, you will have a trust list with a lot of exclusions and a good number of people in your trust list. If you have been around long enough then you should be able to develop a trust network that results in fairly accurate trust scores.
And that's fine... you should be able to add that if you want to. What you should not have is a default setting to have it on when, as a newb, you probably don't even know it exists or how to change it. What you do know, though, is you see red and green shit on the left and assume that the forum itself has determined that that person is trustworthy or not... a newb is typically not going to know that those pretty colors are a result of arbitrary bullshit posted by a select few elite on the forum and is used as a weapon to criticize those that disagree.
If you have it off by default, then anyone who adds it is far more likely to understand what they are adding than those that don't understand the system at all, when on by default.