They are both walled gardens that you have to subscribe to. Since none of the messages can be seen by the public, they both are knowledge silos. Discord has some wonderful instances with smart people, but by its structure even Usenet threads or old SMTP mailing lists are better to search for answers. I'm sure it is against the Discord TOS for an aggregator to scrape and curate its contents. Unlike even HN, Discord messages have an unlimited time they can be deleted punching holes in timelines. Most of the Yahoo Groups that I follow ended up on groups.io
Why do communities even move to Discord? I can't honestly understand it. It has the worst UI ever. Does it have some killer feature others lack?
Discord makes (I would imagine) most of it's revenue from Nitro subscriptions. I don't think facebook has a paid tier.
See https://www.cbinsights.com/research/report/how-discord-makes...
I've had my best Discord experiences when playing games like League of Legends where somebody invited me to a server so we could coordinate better.
I kinda dread "visit our Discord" because sometimes you find a bunch of people with nothing better to do hanging out who aren't knowledgeable or helpful. (I've been that guy in chat rooms before...)
On the other hand I have needed support for open source products like Jellyfin and got good service that way.