For farmers and shitposters, there is another tool called "banning", which I find far more fair and powerful to clean the forum.
Demerit people will have many issues:
- Demerit people for something personal.
- It is going to be difficult to pick all the shitposters in here, for they are too many, and demerit them.
- The merit system is based on reward, not in punishment. So this is going to be against the system existence itself.
Gaining merits may not be as difficult as you find. There are many users in here searching each day for good posts, so just avoid giving lessons to the forum function when is clear you have not enough experience and just do a good work.