The greatest trick the devil ever pulled ... was convincing internet communities to switch from email lists / IRC / another open standard to Slack / Discord. The latest example of a “it's only free while we say it's free" is CNCF’s / Kubernetes's Slack - https://github.com/kubernetes/community/blob/master/communication/slack-migration-faq.md - who it appears have *4 days* to backup their history (for a server with 100,000s of users)
Neither Slack nor Discord are reasonable, serious, professional, options for open community discussion. They are either too expensive, and/or involve inappropriate advertising. And who knows when Discord will start pulling this kind of behaviour, too, requiring large communities to pay?
The problem is today when anyone says "can't we just use an email list?" they are pooh-pooh'ed as being horribly out of touch. Hence why even the linked FAQ describes Discord as the only likely exit plan for Kubernetes. What a mess.