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?
This is objectively not true, because social network effects are in place and there is a switching cost.
That's not the case for open source projects. There are many projects that use Discourse as their primary support channel. There seems to be no dearth of users asking questions there.