Agreed about Reddit. Maybe it's just my specific age (almost 30), but I detest the UX of old mailing list software that shows one email per page. The only thing worse is something like IRC, where you have to hope someone is in the channel with an answer at the exact moment you ask your question, and the logs aren't very practical as a store of knowledge because they're so conversational. Despite a significant interest in retrocomputing, I've never once used Usenet and would actually have to read up on how to start. I think most people my age or younger would be in the same boat with that.

The sweet spot for me would be something like Discourse or even an old-school PHPBB. Slack has a similar problem to IRC - it's ephemeral and the answers don't show up on Google.