As I understood your rank on forum is set by the amount of posts you make and the time since you registered.
But is somebody monitoring meaningfulness of posts? Because in theory I could say "Hi forum" a million times and become a Legend (or what is the maximal rank).
Best Regards
If you spam, you are likely to get banned. Users report meaningless post to moderators, who take action.
Plus you get only limited activity (14 every 2-week period) even if you post a lot of times very quickly.