I do not think that manipulation will be the right word to use for this but little abuse of the merit system is going on for sure. This is evident from threads like :
https://bitcointalk.org/index.php?topic=2896910.0These threads are filled with posts from other members showing how other members are trying to cheat the system. These cheaters are sending merits in bulk to the alt accounts to rank them up. This is additional problem for genuine users as it makes merit more scarce. Also it is very discouraging for members to see these abusers getting away this shameless act.