See, you're assuming that the success metric here is how many people are getting promoted. That's not the metric at all. In fact, quite the opposite. The forum would do well by being more selective.

The previous criteria for rank promotion relied solely on quantity of posts, which led to way too much low quality discussion. With the Merit system, it has added a dimension of quality as well, so you need both quantity and quality.

The goal is definitely not to make sure as many people as possible are getting promoted. The goal is to encourage higher quality posts.