Distributing reddit is a hard problem, but making it anonymous is even harder. It'll be easier to start with cryptographic identities and add anonymity later. In the meantime, users can generate new identities for every action. They will be ignored by other users, since reputation is the easiest way to separate signal from noise.
Building this system will be much easier if you investigate the toolkits for building distributed systems that have been built since Aether started. Ethereum has three building blocks for distributed systems: a blockchain for storing data that requires consensus, like the identities of the creators and moderators of a community; Whisper, a messaging system for sending data that doesn't require consensus, like broadcasting the existence of a sub-forum; and Swarm, a distributed data store for things like discussion archives and the HTML, CSS and Javascript that such a discussion system could be built from to run on every device that every user owns. (For an example of an application with this sort of architecture, see Augur. http://augur.net)
Besides the development speed gained from using these tools, your system will gain benevolent forkability. You want developers with ideas about decentralized communities to write forks that effectively don't steal users since everyone's using the same data sources to read from and write to. But using a homegrown distributed system makes that less likely. If it were built on Ethereum's toolkit, even if a developer disagrees with most of what you've done, it's in their interest to use the same data source even if they rewrite everything. The userbase of benevolently forkable distributed systems never needs to be split, which is a powerful characteristic for growth.
Aether is fantastic, and it's where the web is heading. Good luck!