4 pane comic of dolan on the left and spooderman on the right
pane 1 (dolan): cum join opensurce cummunity!
pane 2 (spooderman): shure! how joyn?
pane 3 (dolan): Here discord! (with discord logo)
pane 4 (spooderman with tears in eyes): y u do dis?
A web forum is far better in most cases. If you can't manage to run your own, there are plenty of lemmy servers that will do it for you. Even an email list (with searchable archives) would be better than Discord.
If you have collaborative documents that outgrow the forum format, use a wiki.
If real-time chat is needed, irc or matrix.
A project hosting its community on Discord is a project that won't get my contributions.
Perfectly summarized and the stance everyone should take for the wellbeing of any community. Look at cs.rin.ru for example.