I know I am a newbie and my opinion doesn't mean shit, but I don't think this will work.
There are a lot of ways to get 1 or even 10 merits and after that no one even cares about shitposting or even getting their account banned. Cause they've done what they wanted to do.

This is my humble suggestion: :
Have a MAXIMUM number of activities or posts for junior and Member ranked profiles in Bitcointalk per week or month.
I see people with 200+ activities and only one merit that they probably bought/scammed someone to get. THESE accounts are the real shitposters.