All-time leader boards tend to become static very quickly as time passes, it becomes impossible for new people to rise above established members who have been adding to their score for years.
It also creates a disparity between premium and free members who don’t have access to using links. I’m not fully knowledgeable on how activity score is calculated but I’m sure it is a factor. The other issue is simply racing through content to achieve a higher score, I’m sure there is way to make it work but not so simple or beneficial as you might first think.