It seems inactive now but Edward Tufte's forum was a great example of this – https://www.edwardtufte.com/bboard – with every single post or comment being made via a basic HTML form and Tufte would then approve everything manually. This resulted in nothing but high quality (and often authoritative) discussions as you knew Tufte was directing it. Indeed, the forum even discussed the topic of content moderation once and Hacker News popped up: https://www.edwardtufte.com/bboard/q-and-a-fetch-msg?msg_id=...

This can't really work at scale, but then would I prefer to frequent a handful of gigantic forums or many Tufte sized hyperspecialized forums..? In any technical field, the latter.