[__MatrixMan__]

At least in what I'm building, you trust the attester because you know them in real life and you share some interests with them, or one of your friends does, or one of their friends does.

As for getting less useful with more precision, I'm not sure I agree. If they're precise enough, you can do predicate logic on them (e.g. prolog):

- mycologist attests about an image: this mushroom is edible

- image ends up on a social feed, a passerby realizes that it's the same image (modulo compression) and attests to that sameness

- I run across the image on a social feed. I have weak trust with the passerby but strong trust with the mycologist. My client can computationally verify the sameness claim, so I don't need strong trust for the passerby (I just needed them for a hint of what my client should verify).

I can then conclude that the pictured mushroom is edible, even though it's not actually bitwise identical to the one that the mycologist asserted about. Without precision, you can't get the predicates to line up for such a derivation.