I think they mean more like, imagine Reddit, but instead of anyone being able to create a new Subreddit on a new topic, it's anyone can create a new Subforum.
Discourse forums still need each owner to set up and pay for hosting.
If only Fandom wikis were unindexable - then they would not be drowining out community run wikis in search results for games where those still exist.
Running a site that is primarily community content and profiting from ads always seems a bit scummy to me. Particularly odd that this one is co-founded by the same Jimmy Wales better known for Wikipedia.
Some examples running it
https://forums.woot.com/
https://forum.newrelic.com/s/
https://community.revolut.com/
https://forums.docker.com/
https://www.discourse.org/