Discord (and other non-indexable chats like Slack) is where conversations go to die and be hidden forever. FOSS and other "open" projects should be using something like Zulip, or even anything else, that can actually be indexed by Google and other search engines.
I'm a part of a few Discords, and questions are repeated over and over again, forever. People who answer the questions, get tired of answering the same thing and eventually stops helping people. In contrast, using Stack Overflow or anything else, people can search Google for answers and actually find it.
~~~Well, besides the whole thing about my previous comment that everything you write in Discord stays in Discord and is basically not findable unless you're already a part of the Discord. While phpbb (or any public forum really) is by default readable by anyone, so searching for questions let you find answers without having to sign in and join the forum.~~~
I'm a part of a few Discords, and questions are repeated over and over again, forever. People who answer the questions, get tired of answering the same thing and eventually stops helping people. In contrast, using Stack Overflow or anything else, people can search Google for answers and actually find it.