Maybe I'm wrong, but after the 'Merit' was implemented, 'Activity' seems had become an unnecessary restriction.
Merit and activity is a two different thing.
Activity count defines potential rank if you are active around the forum for a couple years.
Merit is the ticket to get that potential rank.
It is like taking a higher degree, you take up bachelors to masters and study for years but you need to pass certain exams to achieve the higher title.