... doesn't this already exist?
I mean to say, anyone can already start a website and call it a wiki, set whatever policies they want, synchronize with other websites via RSS feed or whatever, and open it to editing by anyone and everyone (or no one) they choose.
And anyone does. There are hundreds of thousands of wikis out there.
The point of decentralization and federation was to merge the benefits of personal websites - privacy and personal control of your data - with the communication and collaboration powers of centralized social media. So your account is hosted on your instance and under your control and then you can go post on a thousand other instances with that same account. And I don't think it's failed in that.
But wikis are already personal websites. And if somebody wants to federate a wiki they can host it on the same server they have their Lemmy instance on and put a link on the Lemmy homepage.
And the idea that a bunch of people hosting their own wikis with no correction or accountability mechanisms will be less corrupt and have less disinformation then those same people working together to build consensus on the same website? Not persuasive, is all I'm saying.