I've said this a lot in different places and the Lemmy community is so small folks might even recognize me repeating myself, but I'll say it again here. The problem with recommending a good Discord alternative is that Discord is different things for different people. For some it's streaming. For some it's video calls. For some it's voice calls. For some it's DMs. For some it's group servers. For some the image and video sharing is an important aspect. It's hard to recommend a good alternative because you'll always inevitably run into the problem of someone saying "but it doesn't do the thing I use it for." The reality is that folks might need to use multiple apps to meet their needs if they migrate.

If you'd skimmed the article you would've seen they they suggested Discourse which the author openly admits is a forum, not a chat app. But hey, that's what some folks use Discord as.