I actually mostly appreciate the moderation/censorship Reddit does nowadays. E.g. banning subreddits like "beating cr-ppl-s" and "r-p-ng w-men". Isn't the world better of, when it's harder for people to give advice about, and encourage, those things?
Anyway, you wrote (in the blog): "independently hosted forums" — I like that, for various reasons.
Actually, I might slightly have built a Reddit alternative minus single-sign-on. Here's an a bit Reddit like discussion:
https://www.talkyard.io/forum/-61859/forum-software-for-the-...
And one can create per site sub communities, a bit like subreddits. Actually, there are improvements over Reddit: https://www.talkyard.io/-32/how-hacker-news-can-be-improved-... . Someone is actually emailing with me about migrating their subreddits from Reddit to a Talkyard community at their own domain.
You wrote: "It would be a very complicated forum aggregator with a ton of features necessary to create the combined community side like on Reddit or its alternatives." — I agree. And it'd also be lovely with a mobile phone app, that could connect to all these disparate communities. So one didn't need to type the address in the mobile phone browser. Instead one just clicked in a list of recently visited communities. And it showed notifications too. ... A bit like mobile Facebook and Reddit, but connected to 999 decentralized communities.
I've been thinking a bit about building this mobile app, and forum aggregator / search engine. And initially make it work with Discourse (https://www.discourse.org), Flarum (http://flarum.org) and Talkyard (https://www.talkyard.io).