I’m in some Discord servers and Slack channels for online programming classes, but never got into using them much. I think this is partially because in these instances they were mainly being used to institutionalize knowledge (as @Marco_Mandarin-HSK_4 put it), which I think an online forum is better suited for, rather than for real-time communication, which is what Discord/Slack/WeChat were designed for.
If LTL (or a group of LTL students) were to organize any live events (e.g., workshops, movie/game/KTV nights), I could see Discord being beneficial. Otherwise, I don’t see much advantage over a forum and agree with @Michael-Mandarin-HSK_2ish that keeping a community concentrated is generally better.