Lots of useful knowledge hidden behind walled gardens these days.
This has its disadvantages, as you point out, but it also has advantages. What I really like about Discord is the fact that people actually connect with each other. I have never meaningfully connected with anyone on Reddit. Discord enables human connection for two reasons: (1) you have a village-sized group of people, meaning you can actually keep track of individuals and your relationships with them and (2) since it is private enough, you can allow yourself to be more vulnerable.
That's why you use pseudonyms or burner accounts instead of your real name or publicly known handles.
It's only random snippets from a moment in time, which makes me feel like there is a world of useful tips and tricks that is just lost in the stream.
In general, what you'll find there is better and far more up to date than whatever gets mentioned by the few people who bothered to make a video about it on YouTube, which is unfortunately often still more informative than people actually posting answers and tips on public fora.
There are plenty of tools available that can archive everything ever posted in a server. It takes one mad user to collect everything and leak it to the public.
Just like with IRC if you want your chat to be indexed you would need to set that up yourself, but that may break their terms of service.
Now every 'fancy' product has a discord where the same questions get asked every day again and again and the community isn't helpful anymore because it gets tiring.
4chan has a whole lot of non-toxic work safe boards on it too. You won't see much racism on /po/ (paper-craft and origami)
https://www.washingtonpost.com/national-security/2023/12/12/...
On a related note I am very sure that Discord is indeed indexed by the Chinese government, just not for us to see.