Usually everyday people don’t setup forums, that’s the responsibility of the application owner(s) or provider.

By this do you mean official forums? If so I think this is kind of missing some of the independent forums for software (whether games or media players or the like) or other media, which some sorta-everyday people set up in the past. Many have migrated to Discord not only because it’s easy but, I think, because it’s simply more cost-effective.

Forums don’t seem to be cheap. Discourse’s own managed hosting goes for $50 a month, from one of their partners it’s $20, and looks like somewhere in-between if you try to spin it up yourself (e.g. Digital Ocean droplet runs $4 a month, then add in domain, and mail-provider (~$20-35)). Looking at that, it’s little wonder so many either opt for official forums, unofficial subreddits, Lemmy/Kbin communities, or Discord servers instead now.

Maybe if I dug around some more I could find some options for managed hosting (which makes more sense for regular people, I think, to deal with technical maintenance) for Discourse or the like that are cheaper, but I can’t imagine one may find much that beats free. Unless there is something, unfortunately I guess we’re kind of stuck with the situation as-is barring some pleasant exceptions.