I've always wished there was a social network that applied some sort of "I am interested in [person] by [amount]%" premise, but recursively.

E.g., suppose I tell the network that I'm 80% interested in William Gibson, and I set my "see posts by" threshold to 60%. I would then see all posts from William Gibson, as well as any posts from people he's at least 75% interested in. And of course I'd also see posts from more distant connections, if the chain multiplies out to more than my view threshold.

Have any networks ever done something like this before? Or with "interest" swapped for "trust" or some other stat?