In the spirit of the article, how do you start your own community these days? I think it was phpbb that was popular last time I checked (perhaps 15 y ago).
If you don’t mind being centralized Reddit is what really killed forums and is still very good despite a drive to make it worse every year. There are many Reddit clones as well.
And that’s ignoring that phpbb/wordpress are insecure and need patching all the time.
Software changes frequently.