It is heavily abused we can't deny that fact. Because of the
subjectivity. Plus the rules for abusing merit system is certainly not good IMO.
Most of the DT's here or mods only tagged those accounts who were exchanging merits that are connected or has only one owner.
The only thing we could do here is to handout merit to those who we really think contributes something on the said topic and not just because you have the same opinion. On the other hand we can't do something to fix the said abuse. Especially the mutual understanding between two users like:
1. We have the same nationality and handing out a merit to his/er post is a good strategy as that user might also do the same for me.
2. The "indulgence" feeling when somebody handed out you a merit and you are thinking to also give that person to return the favor.
3. The merit gameplayers. (The real toxic users in this forum who will do illegal conversation and trade out merits for their own benefits)