At the beginning when the merit system was new it stopped the account farmers for a while. I'd say the forum gained a couple of spam-free years because of it but since they figured out how to game it, yes that time is over.
This is a point that I still haven't been able to understand, how is the system manipulated?
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Well, it is not rocket science.
If you go to WO or the $100k/push-up challenge topic start posting moon boi messages, you'll farm some serious merits that way. Once you have a main acc that holds considerable amount of merits, you can start building your own alt army and exchange merits between accounts. That's probably what the acc farmers are doing atm. It might sound unreal, non-sense, unworthy to you but some people try it anyway.
You are right some people give merits to short ass moon boi messages a lot and that behavior encourages account farmers but here is the problem, merit distribution is not moderated. Meaning, people can merit whatever post the find merit worthy.
In the end we are almost back to where we were before a decade ago.