I don't know how much of a barrier it'll throw up in practical terms, but getting even a single merit for a lot of these shitposters has proven to be extremely difficult and it would at least be some sort of barrier.  For that reason, I support hilariousandco's suggestion.  He suggested it in another thread and I found it to be a decent idea, since Theymos has ruled out bringing back the newbie jail. 

If it was 5 merits, that'd be damn near impossible for most noobs, but then again ranking up shouldn't be easy anymore, nor should people be obsessing about it.  But they are, and we all know the reason why.