I can find useful discussions from 10 or 20 years ago because they were crawled and archived. IRC, Usenet, web message boards, mailing lists...
Every single discussion happening on Slack or Discord will probably be lost in a year or two and is impossible to find unless you happen to be already aware of it.
Developers should not use these platforms for anything with any value. This is not the way to share information.
I would still have some issues. I do find IRC archives much, much less valuable than more structured sources.
But I'm picking my battles at this point in time. And the lack of indexing is the most critical flaw and one I think is immensely damaging to technical communities on those platforms.
While I enjoy slack at work (not without reservations, but overall I like it), I definitely agree slack/discord are terrible for communities. I can't imagine how much discussion that even I participated in almost 15 years ago is still quickly available, would now be lost to the ether of discord and slack.
This is desirable. I like that my discord conversation will be gone in a few years. They serve little purpose being archived anyway. Old IRC logs are a horrible thing to search for help anyway. Much better just picking a forum/reddit post on the same issue which will be better sorted.
The problem is that for many communities there is only the Discord. Quite technical communities - building projects they obvious feel will have longevity.
Mozilla Hubs springs to mind but there are many more. It's become the norm. It's crazy and more people need to speak out if we're not going to lose a big chunk of a generation's tech knowledge.
I just don't see this being as much of an issue as is stated here. I find that over the years its easier and easier to find info. Github issues, reddit, or stackexchange have huge wealths of info that are expanding rapidly.
I'm talking about communities with very little other material footprint. Nearly all discussion is on ephemeral platforms. There are no other knowledge bases to refer to.
Every single discussion happening on Slack or Discord will probably be lost in a year or two and is impossible to find unless you happen to be already aware of it.
Developers should not use these platforms for anything with any value. This is not the way to share information.