Hey there! My neocities is still under development, but I hope to publish it soon. I was thinking a lot as I worked on my site about this same exact thing. I really, like REALLY REALLY love the small web and especially the neocities subculture of it. But I did notice that it feels a lot more like a collection of people talking into their own respective voids rather than people talking to each other. For all social media's failings, I do feel like I'm really interacting with people. There are guestbooks, and that's cool, but those (and comment sections) are hard to set up, and ironically seem to get harder to set up the more technically skilled you are, because you'll end up being picky about privacy, ethics, implementation details, and so on. (Obviously slathering Disqus all over neocities is completely counter to the ethos of the whole thing.)
I also thought it would be nice to create some sort of SIMPLE social structure - just like you said. Something like webrings, elegantly simple, yet effective. RSS is maybe the best way, I dunno. Sometimes I see blog posts that I'd like to respond to, maybe it's as simple as writing my own blog post and telling the person so by email. It's funny because you could just have the exchange by email, but doing it in public anyways is part of what may make the small web feel more social (in a good way).
That said, my site isn't live...soo....