IIRC, kuro5hin and others all left out a crucial step in the web-of-trust approach: There were absolutely no repercussions when you extended trust to somebody who later turned out to be a bad actor.
It considers trust to be an individual metric instead of leaning more into the graph.
(There are other issues, e.g. the fact that "trust" isn't a universal metric either, but context dependent. There are folks whom you'd absolutely trust to e.g. do great & reliable work in a security context, but you'd still not hand them the keys to your car)
At least kuro5hin modeled a degradation of trust over time, which most models still skip.
It'd be a useful thing, but we have a long way to go before there's a working version.