I think it's a simpler problem: the general public these days uses the internet from phones, not computers with actual keyboards. Phones just discourage longform text and nuance, and encourage 180-character quips and video and image posts. Even if you had a well-moderated forum that kept trolls and bots at bay, the average quality of posts is going to be poor compared to a decade-plus ago. No one yet fully perceived that shift back when Reddit alternatives were first proposed.

Also an entire generation has now been raised ignorant of the concept of a FAQ, because commercial platforms like Reddit wanted people asking the same basic questions over and over again, it was good for engagement metrics. Try to moderate a forum today and close posts covered by a FAQ, and you'll just get young people calling you an overzealous moderator and leaving, because your perspective is unintelligible to them.