there have been dozen of solutions like this since the 90s that came and went. specially during the "browser toolbar era". and there migth be new one poping up now.
in the end it is a privacy nightmare. see stylish extension privacy problems last months.
Yup. Circa 2000 I remember talking with one of those entrepreneurs about joining. He was so sure that being able to comment on everything was a the next step forward in the web. At the time I found the idea both intriguing and suspicious, but the guy, a former surgeon, was such an obvious pain in the ass to work with that it ended for me there.
In retrospect, I recognize it as part of a common genre: grand ideas that are necessary only in theory, not in practice. It's easy enough to add commenting to any web page if the owner wants. It's easy enough to discuss any web page elsewhere, like here. And the grand idea treats good discussion as equivalent to global randos posting comments, which is demonstrably false. Real discussions are gardens that require careful tending.
My first defense now against grand ideas is, "That sounds cool, but who needs it enough to pay regularly for it? And why would this be better for that person than whatever they're doing now?" It turns out that many grand ideas only make sense from a 40,000-foot perspective; if you look at it from the point of view of somebody on the ground, it's obviously just a fuzzy cloud.
in the end it is a privacy nightmare. see stylish extension privacy problems last months.