I was reading a thread in meta where  this problem was raised by a member. Did some research and found a possible abuse case:

Users involved:

https://bitcointalk.org/index.php?action=profile;u=1029845

https://bitcointalk.org/index.php?action=profile;u=962182

See merit history:

https://bitcointalk.org/index.php?action=merit;u=1029845

Member 1 has sent merits to member 2 for total of 10 times and now all posts are deleted. They did this in February and are safe till now.