> Making a more read/annotate/write web is near and dear to my heart

Isn't that basically Wikipedia? I can't imagine a much simpler system that could work at modern web scale.

I think the scale difference is the whole point. Wikipedia has billions of active users, while these Hyperclay-style persistent documents have only a few.

Saying "we don't need this because Wikipedia already solved it" is kind of like saying in 1976: "Nobody needs the Apple II, we already have IBM mainframes that have solved every useful problem in computing much better."