>the whole thing by itself didn't replace in any way what social networks were already offering, e.g. your feed, or direct messaging.

It didn't get to that point, but there's a lot that could be possible if the graph were owned by everyone instead of just the social network owners. Distributed trust, moderation, etc.

Yeah that's always been the dream, but I'm afraid at this point I'm convinced noone wants that, because everyone just wants content to be consumed on their platform, not be available for everyone to reuse and remix on their own.

That's imo the real reason semweb, microformats etc.. failed. We're left with a bit of schema.org that just plays into Google's SEO tactics.