There are a lot of accounts which are posting generic one liners and getting merits for it.
People buy or trade merits for this exact reason - they are shitposters who will never rank up by making a good post, so they buy a single merit or trade with their alts. They need to get to junior member to enable them to take part in some trash bounty campaign.
As Coolcryptovator says, there is very rarely proof that this one merit was bought or farmed, so there is nothing you can do about the individual users. What we need is the requirement for a signature to be displayed to be increased to 10 merit, which would make it far harder to buy or trade, and would make these spammers' merit supply dry up much more quickly. I also feel we should be more liberal with the bans for these spammers. I keep seeing the same names pop up again and again on my report list with the same one-line nonsense, but for some reason we just let them keep going.