Discord is a
trade-off. Don't apply on the wrong problem.
Some pros, I'll pick three. (1) I think the appeal for something like Discord becomes more obvious when documentation feels like a moving target. For example, as a long time back-end developer, I have never disliked StackOveflow more than when I decided to learn front-end JavaScript. Every answer seemed attached to an expiration date. Anything older than 2 years and I'd wonder is this still in effect? I actually wished that JS would have its own special SO where answers can be sorted by "number of votes this year" or a "deprecated" flag. (2) The immediacy of chat, you ask and don't have to wait half a day for someone to notice. (3) No search. It could just be an impression, but my search experience seems to just increasingly suck. Engines seem to struggle to find relevant bits, particularly if the tech is fairly recent and results are flooded with meaningless articles, that just echo the same "Hello, world" from the official documentation. With Discord, I don't have to sort through the junk.
Now the cons.
The chat format for support certainly has its highlights, but you don't have to wear blinders about its downsides. If you allow for time to improve information, information accrues interest. Chat doesn't allow for time. And Discord doesn't particularly care about the quality of information. Discord cares about (authenticated) users showing up on the platform now, now, now. The problems highlighted with the chat format (as it's implemented on Discord), are very focused (though they have ramifications): archiving and searching capabilities are subpar. You show up on some chat channel and ask a question. You get the benefit of immediate advice, by the most authoritative voice that happens to be present. It may be good advice or it may be moot. You just have to take it at face value. On StackOverflow that advice would go unchallenged for a few months, but allow for time and you allow for scrutiny. Eventually, if there's contention, there will be a discussion. Answers are commented upon, improved, deprecated. You can simply show up years later and benefit from the maturation of the different perspectives that contributed to crystallize our current best understanding of the issue.
Obviously, YMMV. Still, don't apply on the wrong problem.