[makin]

I think Archive Of Our Own (AO3) solves a much easier problem (hosting bbcode text), and even then, after many years, they are unable to get enough volunteers to implement a direct message system. It's not quite apples and oranges, but I still don't think the same model could possibly work for Reddit. Yes, Reddit users have made some amazing tools for moderation, but they are still fully dependent on preexisting, complex engineering work by the Reddit employees, including the API. Maybe a better comparison would be Wikipedia, but again, much simpler problem.