Yes, it would be somewhat complicated, but it's not like it would require new computer science. It would probably be revolutionary and destroy the value of the platforms (Twitter, Facebook, etc.) if it were to exist for 5 years in the way I described it and were to be fully developed.

The only problem with such a model is that there is no real incentive for anyone to do all the work, so it would have to be funded like diaspora was, but it's likely it would need $50M in funding. Of course, one could start with a simpler version, but that one would not achieve the full vision. Ultimately, building a Reddit like experience (sans the dystopia) is a lot of work.