Feel free to pick up where we left off, but just know that you're in for a lot of pain on key sync, device pairing, unreliable data availability, poor connection establishment latency, high end-user device resource usage, and very small data indexes which make it nearly impossible to produce even moderately-sized social networks.

I think you're looking at it the wrong way. It's not just hard, but the user experience with it is just terrible. The masses will not use it. If the masses will not use something that requires network effects to be successful, there's no point. These problems may be solvable, but I think I'd trust the opinions of people who have worked on it for years and decided to do something else.