This would never work. They'd just go and spam a bunch of seemingly well-meaning posts elsewhere on this board to get their activity count up to the requirement. Then they'd come to Speculation sub-forum and start trolling. In fact, that's what several of them do today, to fake looking legit.
No doubt. But that is extra steps at least. At the moment, there is 0 effort required. Plus they may end up reported elsewhere before they even post here.