It's a bit dishonestly. When I should be Full Member tomorrow, I will stay a Member with 10 merit and all my 170+ posts where done in past. TO gain 90 merit I need do the same amount of worthwhile posts 
Just write a really, really, really good post and you shouldn't have any problem accumulating 90 merit. And I'm sure if you do create such a post, you'll have made the forum a better place because of it 