Can standard users create channels? I can't seem to figure out how.
And you need to sign up to even see the contents? That's absurd, and I'm sure 0% of it will be indexed for searching for that reason. It's also missing some very basic features like inline links, coloured text, and fonts.
Does Google Groups not support separate, threads? How is a "thread" different than a "topic"?
As for IRC, that's how I'd imagine the Discord chat would be as well, with p2p chat people aren't always eager to talk, but when people do ask questions they're generally answered. As for the server name, you'd still have to know this long ass Discord url.
Which is way more complex than the IRC channel name.
Discord seems to be a somewhat viable alternative to IRC, although IRC has a far stronger foundation and is currently populated.