Please stop using Slack/Discord for forum replacements. Forums can be indexed and found. Slack/Discord is like pissing in the wind. Here today, gone three hours from now.
I generally agree that knowledge-sharing helps more people if it's easily searchable via Google, but then again, it's also possible that the interactions would be different without the exclusivity. Many events in the community's history may have never happened if it were more public.
I always thought it was replacing irc and other previous chat platforms (google chat, hipchat, skype, icq, etc)?