Phpbb-style forums are a mess. Simultaneously too ordered and not ordered enough - you don't get threaded replies, but you do have to put everything in the right topic and the right forum. No notifications that do the right thing.
For years I remember forum makers refusing to offer a "just notify me when someone's replied to my question, otherwise don't bother me" feature on the grounds that it would destroy participation. IMO the main reason Reddit won is that it offered just that.