Forums are linear and your are expected to have read all the post to post in one thread. There is also the old members who nag you into not creating a new thread but use the search tool to comment on an old one. There is forum local stars that control the discourse far more than on subreddits, and the photo + footer customization make them more prone starification and to group think.

On subreddit freshness is always welcomed even it is an old subject with a different spin. You are not expected to present you, there is no random subforum, you can be focused.