As to the topic at hand:
I have severe doubts as the, well, merit, of the merit system. I've seen several systems implemented to restrict spam or low quality posts over the years, and they have all come to naught sooner or later.
The reasons for that are many, but the biggest one, in my opinion, is not a negative. There are a lot of clever people here, and they will figure out how to game the system. Whatever the system is. There are many things that can be said about the denizens of bitcointalk, but for the most part they are not sheep.
Let it play out. Theymos does keep an eye and an active hand on his creations. It will work or it won't.
I am not aware of the earlier methods you are talking about as I joined recently. But I think the merit system is designed after giving it la lot of thought as:
1) This system is designed in a way that it will keep getting better with time on its own. The alt accounts, account farmers will spend the default merit they got soon. They will also fail to get merits from merit sources as they will not be able to post good quality posts. If they start improving the post quality, that is an additional benefit.
2) All the new registrations will now be careful from start with their posting. Less work for moderators which can utilize for other important tasks.
3) The merit system system actually has resulted in automated moderation with the help of existing members.
4) Finally, let me explain regarding members going to game this system as well. It is not happening actually which is evident from the complaints we are getting from so many new members that they are not able to rank up.