At this point you can say that you'll argue your case in a future post instead of replying to this comment.

I will, but I'll answer you here anyway -- sorry for taking so long to reply.

I strongly disagree that NNTP is a good choice for a backend standard

I feel I should clarify that I don't think it's "good", so much as "less bad than the alternatives".

But we don't need to deal with the problems of distributed systems, because web forums aren't distributed!

Well, yes and no. Part of what got me on this track in the first place is the distributed nature of the diaspora. We have a network of more-and-more-loosely connected subcommunities that we'd like to keep together, but the diaspora authors like owning their own gardens. Any unified system probably needs to at least be capable of supporting that, or it's unlikely to get people to buy back in. It's not sufficient, but it is necessary, to allow network members to run their own server if they want.

That being said, it's of interest that NNTP doesn't have to be run distributed. You can have a standalone server, which makes things like auth a lot easier. A closed distribution network makes it harder, but not that much harder -- as long as every member trusts every other member to do auth honestly.

The auth problem as I see it boils down to "how can user X with an account on Less Wrong post to e.g. SSC without needing to create a separate account, while still giving SSC's owner the capability to reliably moderate or ban them." There are a few ways to attack the problem; I'm unsure of the best method but it's on my list of things to cover.

Given all of this, the only possible value of using NNTP is the existing software that already implements it.

This is a huge value, though, because most extant web forum, blogging, etc software is terrible for discussions of any nontrivial size.

There's probably an existing standard or three like this somewhere in the dustbin of history.

Is there?

That's a serious question, because I'd love to hear about alternative standards. My must-have list looks something like "has an RFC, has at least three currently-maintained, interoperable implementations from different authors, and treats discussion content as its payload, unmixed with UI chrome." I'm only aware of NNTP meeting those conditions, but my map is not the territory.