Totally agree with you, I think the merit system will just lead to one result that little people can get a rank rise and most of them will leave this forum, besides, new users will have little interest to enter in, so the forum will have less and less active user
You are missing a point! The forum need constructive, helpful users, so users who un-constructive, helpless should leave. No one in the forum need sort of members. In addition, it might be better if users are active in the forum, but it doesn't matter if they are not active daily. The most important thing is during the time they active in the forum, they are able to contribute to the forum with their constructive, helpful threads.
Newcomers are welcome, but if they are spammers, cheaters, they should not join the forum or should leave soon after joining.