I guess the U18 2's thread was a steady stream of posts each week over an entire year, whereas there have been plenty of other high-impact threads over the years which have captured the attention of posters for a few days (or weeks) then died down.
The U18 2's thread was also consolidated (IE - all posts were in that thread - whereas the Lightning topic at the moment, has people posting in a few different threads).
As far as most interest, I would suggest the peak was around the time of the sale of the 36ers, Lightning etc.