I think the biggest thing holding back the development of the next generation of social networks is this pernicious belief that it is mandatory to put some sort of public comment section on everything, where anybody with a pulse (or the technical wherewithal to fake it adequately enough) can slap anything they want down next to your content. Context matters, and this has a certain inevitable effect even on the original content.

It is a tool. It has times and places. It is not mandatory, nor is it always a good thing. It is quite often a really, really bad thing. It can always be adjoined to a piece of content, like we're doing right now. It is not mandatory for the original poster to host it.

If you want a social network that works that way, you are spoiled for choice. If you are unhappy with those social networks, consider the possibility that much of your unhappiness may in fact stem from this very idea. If it seems like everywhere you go is kind of a cacophony of regression-to-the-mean discussion, insults, lowest-common-denominator... this is the root cause.

It is not a bad thing that "replying" to the creator of an RSS-based blog is exactly as hard as they choose to make it, up to and including making it impossible.