Merit is designed with the intention of trying to tackle this but it will take some time. I think the biggest change will come when signature campaigns start to only accept members plus (yes I see that happening because JR's can no longer have links in their signatures). At that point it will be pointless posting on an account below member unless it's something constructive. Of course there will still then be many members+ who are in signature campaigns but it will certainly be a start.
Merit will only stop people mass farming as many accounts as they like. It also doesn't stop older members who already have achieved enough merit either and believe me there's a lot of senior and hero member shitposters. I think the main issue now is clamping down on poorly run campaigns and their managers as it's their fault we're in such a mess in the first place. If campaign managers did their job properly and only paid for quality posters and posts then the forum would clean itself up pretty fast. It's only because we have crapcoin campaigns with little to no management that we're in such a predicament. Punish those campaigns and their managers and you'd soon notice the difference.