I also desperately want something like this to succeed. I want to be able to see others' reactions on
all NYTimes articles, for example, not just the handful each day they enable comments on, or the occasional one submitted to HN.
And I want it to have all of the standard functionality -- hierarchical comments (like HN and Reddit), upvoting and downvoting, auto-collapsing tangential threads with less votes (like Reddit), giving more weight to users who are consistently upvoted, etc.
But also, I'm not sure if URL's are exactly the right pieces of content to associate with. Not only do you have the problem of determining canonical URL's when sites themselves don't provide them as metadata, but there's a lot of content out there that isn't a webpage: TV episodes, TV series, movies, podcast episodes, podcasts, music tracks, music albums, and so forth. Right now the closest thing there is for some of those (some TV episodes, some podcast episodes) are official posts in dedicated subreddits.
It almost makes me wonder if it would need some kind of dedicated URL scheme that could be managed by Wikipedia or MediaWiki or something, like tv://startrek-strangenewworlds.us.2022/s02/e03#tomorrow_and_tomorrow_and_tomorrow.