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?
On the bright side:
Aggressive garbage collection and automatic thread locking are optional settings in most web forum software I've seen.
Lemmy shares some of the important parts of Usenet, and could develop into something that comes close.