If I understand correctly, then the guy who likes to read occasionally to write posts to gain activity will never go on to the next rank unless he writes interesting and informative posts 
Composing, writing good, high-qualitied posts first. Then you have to wait for luckiness, chances to come. Those ones will determine whether you can get merits from others or not. This system is not a perfect one, in terms of missed good quality posts which wont get merits,right? However, merit system is good for the forum at least in the purpose of getting rid of abundant spamming, non-sense, off-topic posts.