more than the required posts
The problem is a qualitative one. That is to say, the continued shittiness of bitcointalk has to do with how bad the posts here are, not how many of them there are. Your solution would only make this problem worse, because then users would be motivated to make way more posts than whatever their maximum is for whatever campaign they're in. That certainly won't help the quality of the forum as a whole.
Do you not realize why the merit system was implemented in the first place? It was an alternative to DT members red-tagging shitposters. It's a solution that doesn't have to make a mockery of the trust system, and I think it's one that will work, given enough time to play out.
These threads suggesting fixes to the merit system that promote laziness and go against the spirit of what it's about drive me nuts. Just be patient and earn merits like everyone else.
Mine does, DarkStar_ is good for doing that.
And that *only* works because he doesn't accept shitposters to begin with. Can you imagine what would happen if something like what OP suggested was adopted by these awfully-managed altcoin bounties? It would be a never-ending waterfall of shitposting, because these dolts would be incentivized to blow past their quotas, and meanwhile they still haven't mastered the English language.
Why don't they chuck them out of the programme if they can't earn any merit?
Now you're on to something....