Or even better, they could've used usenet. Usenet has all the benefits of automagically scaling (due to federation) and no worries about the issues of self-hosting (security, updates, etc) but also isn't run by any single company or person. The open protocols of the past are so much better than the proprietary corporate software services of today.
I have been wondering why Usenet and IRC haven't experienced a resurgence. Discord will be the next casualty of corporate greed. It's really a fallacy that these communities are moving to yet another corporate-controlled entity.
There were in the past - Slack basically bootstrapped itself off the back of techies, with the IRC transport making Slack seem like a prettier IRC... only to shut down the IRC transport once they've entrenched themselves on the market.