I am not sure if blockchain is the best example. It applies, yes, but in blockchain Proof of Work the control tends to aggregate to the miners, and only the very big ones there have real monetary incentive to keep mining (there is ample speculation on whether Bitcoin would be prone to a 51% attack enabled by a price devaluation, miners dropping out, and then one big player suddenly brings all his/her processing power into play). I am not the expert, though, and deliberately keep my distance for various reasons.
PeerTube is a good example, though.
There are others with intentions to offer similar things (but not sure on the status of that), like Dat Foundation who use gossiping to spread information (they just revamped their core, and have a much more solid basis now) and Secure Scuttlebutt, also gossiped peer-to-peer, who have Pubs where things can be aggregated.
I also got interested for safe network after seeing it discussed on Solid forum and featured on Hacker News (the first comment on HN sets it away a ‘yet another alt-coin scam’, but I’m intrigued whether that is the case. That may be too quick a conclusion).
@strypey re: Loomio Open App Ecosystem. You may be interested to watch this video by Glen Simister. I will post to Loomio too. It is based on safe network, but he is now creating cool stuff for Solid Project.
Would be very interesting to see something recommendation-engine-like appearing in the fediverse, indeed.
Edit: Here’s my post on Loomio in the A Public Resource Management System thread.