But since people believe more posts will increase their chance on getting merrited, isn't this proof that this system is not working? I believe it is.
No, it's proof that a lot of people are stupid.
You must know the quote:
Insanity: doing the same thing over and over again and expecting different results. - Albert Einstein
Eventually, after shitposting relentlessly they'll work out they need to do something other than more shitposting to get merit.