Such a rudimentary system existed in the 1990-ies as I said before: it was called usenet, and had a simple, decentralized protocol: NNTP.
Afaik, NNTP is not decentralized consensus. Rather it is a single news server which is the canonical source and other servers can mirror it.
Nope. It was, AFAIK, totally decentralized. You posted your post to the news server your reader was connected to, who then propagated it in a P2P network of news servers. You could run your own news server of course but only institutions did so, because that was "heavy" at that time for the existing technology in those days. In fact, it would even be "heavy" today too. Bitcoin's block chain is ridiculously small compared to the news groups' daily volume. That said, a news server mostly didn't keep old stuff. One month of history was usually standard. If you wanted to keep stuff, it was entirely your business.
The "consensus" was simply everything, because there was no specific order needed, there was no contradiction to be resolved etc...
Of course, every news server could decide for himself whether he propagated the article or not, but the standard policy was to propagate everything. There was no crypto needed for that. You didn't need an "account". Everyone could just post and put the "credentials" he liked - but of course, nobody would stop you from signing your messages.
No wonder it was a clusterfuck failure. Anyone could then act as an imposter for anyone, and other inconsistencies such as people could post in the future dated as if they had responded in the past, thus pretending to be able to predict the future.
Also there is no guarantee that any server is giving you the full or even correct data!
As I explained to @Theymos, it is really impossible to do coherent decentralized databases without the decentralized consensus.
Actually P2P is not decentralized consensus, which was my claim.
and that is something you cannot solve without human moderation.
Which can be accomplished in a decentralized forum.
Slight improvements of usenet would have implemented the features you are longing for, like multiple versions of moderated groups with different moderators, but visibly there was not enough demand for that.
I don't expect a lot of demand for that feature either. As
I had detailed in my Bitcoin killer thread, I think the two choices 1) group leader's (aka thread creator's) moderation and 2) no moderation will be the most popular choices and #2 is very important bcz as you found out that when a post is deleted in self-moderated thread on BCT, the post disappears from public accessibility. Some users might want to toggle the "no moderation" to glance at what is being deleted by default by the group/thread moderator.
Yet when I build something, I might as well build the generality because the market can sometimes surprise and find uses for things we didn't envision.
I think we might also find that some superstars become frequently chosen moderators, so the generality might actually end up being used.
I only wanted to point out that decentralized discussion platforms existed in the 80-90-ies and essentially disappeared, which indicates the relatively low value people attach to this decentralized paradigm.
Aliasing error again. You have really bad hole in your intellect pertaining to jumping to conclusions that fit your confirmation bias without considering all the possibilities. You need to look at that stuck clock once every 12 hours.
They didn't fail because they were decentralized. They failed because they sucked. Also there was no legitimate known need for being decentralized at that time. Some decades later, we now understand that centralized databases are a major liability.
Most importantly, people will earn tokens which is one thing that will motivate them to use it.

And the superstars will earn tokens. Where the superstars go, the flock follows.
Also the decentralized database means a plethora of GUIs and apps on top of the same database, so that network effects kick in and the users are getting more of their choices met than @Theymos could possibly keep up. The real reason users need decentralized DBs is not because they care at all (they don't!) but the users do care about competition and getting more apps and more features faster.
And so now all those fucking B-listers can go fuck themselves because I actually do know what I am doing.