Why? In open source, many communities now have moved from IRC to discord, a very sad move if you ask me. I think it will also become increasingly relevant for professional networking in the CS world.
If the open source project is serious about building a compelling community that people would actually hang out at, they'd consider Discord/Slack.
Elm lang has an IRC channel. Like all IRC channels on Freenode, it's pretty much dead. One reason being that only a small fraction of people even are willing to use IRC, mostly because they're old enough to know wtf it is.
But then the Elm creator started a Slack server. ...And it's absolutely bustling. There's people getting help. There's people giving help. There's people golfing code or discussing design ideas. There's people sharing their projects and receiving feedback. There's different channels. There's people meeting people and making friends. There's people sending messages to offline users and offline users able to read them when they come back online. And there's even people posting multiline code snippets, something that tends to come in handy for a software project of all things.
There's people who want to grow an online community, they tend to discover Discord very quickly. No brainer. And then there's people who want to convince an increasingly empty room that the application layer protocol behind the community is what matters most.
