Yes, it's a good idea. It has some security and privacy considerations of its own which are outside of my area of expertise, and I believe it could be implemented on top of the existing spec.
That's actually a pretty good idea. I'm sure there are some implementation problems I haven't thought of yet, and ways for companies to get around it, but on the face of it a really good idea.
I really wish your comment said "There would be no feasible way to implement such a system because <X>, and it probably wouldn't be desirable because <Y>." I said "maybe this would be good" in hopes that others would have interesting ideas about whether or not it would be.
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