Reddit's charm is that you can easily discover brand new communities and it's zero friction to get involved, you find a new subreddit and start interacting. No need to remember the new site or set up new credentials. A bunch of different communities adds all that friction back in.

I agree with your first statement. For years, I have been working on a website/app/community platform to support learning and debate about the productive uses of nuclear energy.

My vision is more of a combination of the best of Reddit, online courses, blogging, photos, video, learning games, and simulations. More of a slice across many different types of app, tuned to the topic at hand that interests me. It's fun to work on, even if my progress is slow.

Reproducing r/nuclear seems like a nightmare scenario. Lots of arguing. Tough to control the tone and screen out-dated information. It's the classic problem with social media, discerning the difference between reality and myth. Plus, reading through screaming matches is not a fun way to learn.

Aggregating these smaller nightmarish sites, who wants to do that?