@HerraBRE A single universal "trust score" would indeed be ridiculous or even dangerous.
But say you would like to get the opinion of someone knowledgeable about a subject you are not familiar with. How do you do it? Ask around, right? And the recommendation you may get (if you are lucky) is for a specific subject, today. That might be feasible technically. I recently came across this post which touches the question: https://medium.com/@bblfish/what-are-the-failings-of-pgp-web-of-trust-958e1f62e5b7